UC-NRLF 


511 


LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 


Class 


SPECIFICATIONS 

FOR 

STREET  ROADWAY 
PAVEMENTS 


BY 

S.  WHINERY 

M.  Am.  Soc.  C.  E. 


NEW  YORK 

THE  ENGINEERING  NEWS  PUBLISHING  COMPANY 
1907 


SPECIFICATIONS 


FOR 


STREET  ROADWAY 
PAVEMENTS 


BY 


S.  WHINERY 

M.  Am.  Soc.  C.  E. 


NEW  YORK 
THE  ENGINEERING  NEWS  PUBLISHING  COMPANY 

1907 


rr*' 
i 


Copyright.  1907, 

BY 
THE  ENGINEERING  NEWS  PUBLISHING  Co. 


TABLE  OF  CONTENTS 


INTRODUCTORY. 

Page 
Value   of   Standard   Specifications 5 

Theory  of  Specifications 5 

Should   be   Full   and   Complete 7 

Should   be   Enforced 7 

Reasonableness    of    Specifications 8 

SPECIFICATIONS. 

General —  Page     Sections 

General  Description  of  Work ~ 9 

General    Provisions 9  1-3 

Inspection    10  4 

Injuries  to  Persons  and  Property 11  5 

Public   Convenience  and  Safety 11  6-8 

Other    General    Provisions 12  9-19 

Incidental  and  Extra  Work 14  20-21 

Curbing  to  be  Set  in  Advance 14  22 

Preparing  the  Sub-Grade 14  23 

Foundation*! — 

Concrete  Foundations;  Portland  Cement 16  26 

Sand 17  27 

Broken    Stone 18  28 

Concrete,  Composition  and  Preparation  of 18  30-35 

Foundation   of  Old   Paving   Stone 20  36 

Foundation   of   Broken   Stone..  22  37-38 


166790 


Bituminous  Pavements  —  Page     Sections 

Classification  of  Bituminous  Pavements  ..................  23  39 

Asphalt    Pavement  .......................................  24  40-57 

Crude  and  Refined  Asphalt  ..............................  25  41-44 

Petroleum    Residuum    Oil  ................................  27  45 

Sand    ...................................................  27  46 

Pulverized    Stone  ..................................  ......  29  47 

Stone   for   Base   Course  ..................................  28  48 

Asphaltic   Cement  ........................................  28  49 

Surface  Mixture  .........................................  28  50 

Base    Course  .............................................  29  51-52 

Laying    the   Pavement  ...................................  30  53-55 

Street    Railroad    Tracks  ..............  ...................  32  56 

Plant     ..................................................  32  57 

Rock  Asphalt  Pavement  ...........................  :  .....  33  58-62 

Block   Asphalt   Pavement  .............  ...................  35  63-69 

Granite,  Briek  and  Wood-Block  Pavements  — 

Granite  Block  Pavement  ...............  .  .  .  .  ..............  38  70-81 

Brick   Pavement  .........................................  43  82-93 

Wood-Block   Pavement  ...................................  48  94-104 


General,  Relating  to  All  Pavements  ................  .  .....  53  105-108 

•Payments    ..............................................  54  10g 

General  Specifications  for  Experimental  or  Untried  Pave- 

ments   ...............................  55  110-112 


* 

or  THF 

f    UNIVERSITY 

' 


INTRODUCTORY. 

In  addition  to  their  value  as  memoranda  and  aids  in  preparing 
specifications  for  a  particular  project,  carefully  prepared  general 
specifications,  embodying  the  latest  approved  practice,  sometimes 
supply  the  most  useful  and  acceptable  brief  treatises  upon  any  par- 
ticular branch  of  engineering  work.  It  has  been  partly  with  this 
thought  in  mind  that  th.e  following  set  of  specifications  for  standard 
street  pavements,  has  been  prepared  and  is  now  offered  to  city 
engineers  and  municipal  authorities. 

To  widen  their  range  and  increase  their  usefulness,  copious  foot 
notes  have  been  added,  referring  to  alternative  requirements  and 
methods  of  construction,  and  giving  some  of  the  reasons  for  the 
preference  or  adoption  of  the  construction  called  for  in  the  speci- 
fications. It  is  recognized  that  in  a  good  many  matters  of  detail 
embraced  in  these  specifications  there  is  difference  of  opinion  among 
able  engineers,  many  of  whom  are  at  least  as  competent  as  the 
writer  to  determine  what  is  best.  They  are  not  offered  in  a  dogmatic 
spirit,  or  with  the  hope  that  all  the  provisions  found  therein  will  be 
accepted.  If  they  shall  be  of  some  assistance  in  bringing  about 
correct  standards  for  such  specifications,  their  preparation  will  have 
been  justified. 

Theoretically,  three  general  classes  of  engineering  specifications 
may  be  noted.  In  the  first  the  aim  of  the  engineer  is  to  specify  the 
end  or  result  that  it  is  desired  to  secure,  leaving  the  contractor  free 
to  originate  and  follow  the  methods  by  which  these  results  are  to 
be  attained.  In  the  second  the  engineer  aims  to  secure  the  desired 
end,  by  specifying  in  detail  the  materials  and  the  methods  which 
in  his  opinion  will  accomplish  the  purpose,  he  himself  assuming 
responsibility  for  the  results.  Either  of  these  two  classes  of  speci- 
fications is  permissible,  and  the  engineer  may  choose  the  one  which 
in  his  opinion  seems  best  adapted  to  the  character  of  the  work  to 
be  done,  and  the  conditions  under  which  it  must  be  prosecuted. 

In  the  third  class  of  specifications,  met  with  more  frequently 
than  they  should  be,  the  engineer  undertakes  to  prescribe  not  only 
the  character  of  the  materials  to  be  used  and  the  methods  to  be 
pursued,  but  also  the  results  to  be  attained.  The  position  thus 
assumed  is  illogical,  and  often  unreasonable,  and  may  lead  to  com- 
plications between  the  engineer  and  the  contractor.  If  a  contractor 
be  required  to  turn  out  a  product  which  shall  conform  to  certain 
standards,  he  may  properly  be  given  much,  if  not  full  latitude,  as 
to  how  the  stipulated  results  shall  be  secured,  and  may  be  held  fully 
responsible  for  the  outcome;  if  on  the  other  hand  the  engineer 
chooses  to  specify  with  more  or  less  minuteness  the  character  of  the 


6 

materials  to  be  used  and  the  methods  of  construction  to  be  followed, 
and  enforces  compliance  therewith,  it  seems  fair  and  just  that  he 
should  assume  responsibility  for  the  results  produced,  and  therefore 
unfair  to  hold  the  contractor  to  responsibility  for  consequences 
arising  from  the  use  of  materials  and  methods  which  he  was  allowed 
no  choice  or  latitude  in  selecting. 

In  street  paving  work,  of  well-known  and  standard  character, 
the  second  class  of  specifications  seems  preferable  for  a  number  of 
reasons,  the  leading  one  being  that  the  time  required  to  develop 
the  good  or  bad  quality  of  the  work  must  usually  extend  over  a  con- 
siderable number  of  years,  and  the  conditions  to  which  the  pavement 
may  be  subjected  in  the  meantime  are  likely  to  vary  so  widely  that 
it  may  be  very  difficult,  if  not  impossible,  to  prescribe  a  satisfactory 
standard  of  service  and  endurance.  Disputes  are  therefore  liable 
to  arise  between  the  municipality  and  the  contractor  as  to  the 
latter's  liability,  or  conditions  may  make  it  difficult  or  impossible 
to  hold  the  contractor  to  strict  account  for  that  liability. 

It  is  believed  that  in  the  present  state  of  the  art  it  is  entirely 
practicable  to  so  frame  specifications  for  the  materials  to  be  used 
and  the  methods  to  be  followed  in  the  construction  of  street  pave- 
ments, and  to  so  enforce  compliance  therewith,  that  the  engineer 
and  the  municipality  may  safely  assume  responsibility  for  the  quality 
of  the  work  produced.  While  it  may  be  true  that  local  conditions 
sometimes  make  it  very  difficult  to  enforce  compliance  with  speci- 
fications, the  same  conditions  are  likely  to  make  it  at  least  equally 
difficult  to  secure  effective  responsibility  on  the  part  of  the  con- 
tractor for  any  long-period  guarantee  of  the  work  done  by  him; 
and  the  contractor  who  negligently  or  purposely  violates  the  speci- 
fications during  construction  is  not  likely  to  be  more  faithful  or 
scrupulous  in  living  up  to  any  guarantees  he  may  make  with  regard 
to  the  future,  even  where  the  terms  and  conditions  of  such  guar- 
antees may  be  clearly  defined  and  indisputable.  The  writer  has  dis- 
cussed the  subject  of  time  guarantees  as  applied  to  street  pavements 
pretty  fully  in  his  book,  "Municipal  Public  Works,"  and  the  above 
brief  statement  seems  all  that  is  necessary  here. 

In  conformity  with  this  view  of  the  matter,  the  following  speci- 
fications aim  to  set  out  as  definitely  and  clearly  as  practicable  the 
requirements  for  the  construction  of  good  pavements  of  the  several 
standard  kinds,  and  it  is  assumed  that  the  engineer  will  be  able  to, 
and  will  enforce  them. 

It  is,  however,  not  infrequently  the  case  that  circumstances  will 
compel  the  engineer  to  provide  for  the  construction  of  new  kinds  of 
pavement,  the  value  and  usefulness  of  which  have  not  been  deter- 
mined, and  for  which  experience  has  not  furnished  the  necessary 
data  to  enable  him  to  prepare  adequate  specifications.  In  such  cases 
the  wisest  course  to  follow  is  to  specify  results  only,  safeguarding 
the  interests  of  the  Municipality  as  fully  as  possible,  and  throwing 
upon  the  promoter  or  contractor  full  responsibility  for  the  materials 
used,  the  skillful  construction  of  the  work,  and  the  utility  of  the 


product.  A  proposed  form  for  a  general  specification  of  this  char- 
acter will  be  found  at  the  end  of  the  set. 

No  attempt  has  been  made  to  submit  specifications  for  pro- 
prietary or  patented  pavements,  or  those  composed  wholly  or  in 
part  of  materials  which  are  patented  or  protected  by  trade-marks. 
The  owners  or  contractors  engaged  in  constructing  these  pavements, 
often,  if  not  usually,  claim  the  right  to  dictate  the  specifications 
under  which  the  work  shall  be  done,  and  the  municipal  engineer 
who  is  called  upon  to  construct  such  pavements,  must,  in  each  case, 
determine  whether  the  specifications  offered  are  adequate  and  satis- 
factory. In  many  cases  the  form  of  general  specifications  for 
"untried  or  experimental  pavements"  given  herein  may  appropriately 
be  used. 

The  engineer  is,  in  common  with  all  men,  fallible,  and  he  can 
hardly  hope,  in  the  preparation  of  specifications,  to  make  them 
perfect;  to  cover  every  item  and  particular;  or  to  escape  some 
ambiguities  of  expression,  and  some  degree  of  indefiniteness.  The 
writer  can  only  claim  that  he  has  aimed,  in  the  light  of  a  consider- 
able experience,  to  set  out  as  fully  and  definitely  as  practicable 
the  requirements  for  the  proper  construction  of  high-class  street 
pavements,  and  has  endeavored  to  avoid  loose  or  obscure  terms  and 
expressions.  The  ideal  specification  is  one  that  furnishes  a  wholly 
sufficient  guide  to  the  accomplishment  of  the  desired  purpose;  that 
provides  for  every  possible  contingency  which  may  arise,  and  is 
couched  in  language  which  not  only  means  exactly  what  it  was 
intended  to  mean,  but  is  incapable  of  any  other  interpretation.  It 
is  needless  to  say  that  no  example  of  such  a  specification  can  be 
instanced  as  a  model. 

It  has  been  the  aim  to  make  these  specifications  fair  and  just 
to  the  contractor;  that  is,  to  require  of  him  no  impracticable  or 
indefinite  service,  or  the  assumption  by  him  of  risks  other  than 
those  fairly  involved  in  the  conduct  of  the  work. 

If  the  plans  and  specifications  for  any  work  which  a  contractor 
bids  upon  are  so  full,  specific  and  clear,  that  he  may  know  exactly 
what  he  will  be  expected  to  do,  and  if  they  do  not  require  him  to 
assume  unusual  chances  and  risks,  he  may  intelligently  name  prices 
which  he  believes  will  compensate  him  for  the  service.  Having 
done  so,  his  proposal  having  been  accepted,  and  a  contract  entered 
into  accordingly,  the  engineer  and  the  municipality  have  a  right 
both  in  law  and  equity  to  demand  that  he  will  do  exactly  and  fully 
what  he  has  contracted  to  do.  No  excuses  on  his  part  can  be  valid 
and  none  should  be  accepted.  He  may  in  all  fairness  and  justness 
be  required  to  "toe  the  mark"  strictly.  To  the  neglect  to  recognize 
and  enforce  these  principles  is  chargeable  the  greater  part  of  the 
poor  and  unsatisfactory  work  so  common  in  street  pavement  work 
in  our  cities.  Unexpected  contingencies  may,  of  course,  arise  where 
some  changes  and  concessions  may  be  proper  and  just,  but  these 
should  be,  and  usually  are,  very  rare.  On  the  other  hand,  sweeping 
general  clauses  in  contracts  and  specifications  intended  to  catch  the 


contractor  "goin'  or  comin',"  unnecessarily  stringent  stipulations 
which  were  never  intended  to  be  strictly  enforced,  hut  were  put  into 
the  specifications  with  the  idea  that  they  would  help  hold  the  con- 
tractor up  to  a  high  standard,  and  "one-sided"  contracts  intended 
to  give  the  municipality  an  unfair  advantage  over  the  contractor, 
are  as  inadvisable  in  policy  as  they  are  wrong  in  principle.  Nothing 
should  be  put  in  a  specification  that  is  not  clearly  essential  to  secure 
the  results  aimed  at,  and,  this  having  been  done,  every  requirement 
should  be  enforced.  The  existence  in  specifications  of  requirements 
that  are  not  intended  to  be  enforced,  gives  the  contractor  a  pretext 
for  neglecting  others  that  may  be  important. 

In  these  specifications  will  be  found  a  number  of  details  that 
are  often  not  regarded  as  important  and  which,  when  found  in  pav- 
ing specifications,  the  contractor  is  frequently  allowed  to  ignore. 
In  the  writer's  opinion,  based  upon  his  experience  in  street  paving, 
every  one  of  these  requirements  are  essential  to  the  production  of 
high-class  work,  which,  it  is  hardly  ncessary  to  argue,  is,  in  the  end, 
the  most  economical  work  from  the  standpoint  of  the  municipality. 

It  may  be  argued  that  the  adoption  and  enforcement  of  these, 
specifications  would  have  the  effect  of  raising  prices.  In  many  cases 
this  would  doubtless  prove  true.  Contractors  are  entitled  to  a  fair 
and  reasonable  compensation  for  their  services.  It  is  admitted  that 
in  some  cities  the  prevailing  prices  for  some  kinds  of  pavements 
are  below  the  actual  cost  of  the  work  if  it  were  done  in  a  proper 
manner,  conforming  strictly  to  the  specifications.  Illogical  as  it 
undoubtedly  is,  the  low  price  at  which  work  is  taken  is  sometimes 
considered  a  sufficient  reason  for  accepting  work  below  standard. 
The  consequence  is  that  bidders  not  only  count  upon  concessions 
and  lax  enforcement  of  the  specifications,  but  bid  lower  and  lower, 
expecting  that  further  concessions  will  enable  them  to  get  out  with 
an  undeserved  profit.  This  is  one  of  the  most  serious  evils  in  the 
paving  business  to-day,  and  the  highest  public  interests  demand  a 
thorough  reform.  Low  first  cost,  desirable  as  it  may  be,  is  the 
poorest  economy  if  it  be  secured  at  the  sacrifice  of  the  quality  of  the 
work.  If  one  pavement  costs  twenty  per  cent,  more  than  another, 
but  renders  forty  per  cent,  more  service,  it  is  obviously  the  cheaper 
of  the  two. 

Contractors  are  prone  to  contend  that  this  or  that  provision 
in  a  specification  is  unusual,  unnecessary  or  unfair.  In  dealing  with 
them  the  engineer  should  bear  in  mind  that  no  requirement  of  a 
specification  which  is  clearly  and  definitely  stated  so  that  the  bidder 
may  understand  exactly  what  it  means  and  what  he  will  be  expected 
to  do,  and  may  frame  his  prices  accordingly,  can  be  unreasonable 
or  unfair  to  the  contractor.  Unusual  or  unnecessary  requirements 
may  result  in  unwarrantably  increasing  the  cost  of  the  work,  and 
this  may  raise  a  question  between  the  engineer  and  the  municipality 
employing  him,  but  it  can  furnish  no  occasion  for  questions  of  fair- 
ness or  unfairness  between  the  contractor  and  the  engineer. 

NEW  YORK,  Dec.  27,  1906. 


SPECIFICATIONS. 


For  Grading  and  Paving,  or  Repaying 

with Pavement 

on  a Foundation,  the  Roadway 

of 

Street,  from    

to 

together  with  all  work  incidental  thereto. 


General  Description  of  Work. 

The  work  embraced  in  and  to  be  done  under  this  contract  con- 
sists of  grading  the  entire  street  from  curb  to  curb  between  the 
limits  named,  including  the  removal  or  readjustment  of  the  pave- 
ment now  on  the  roadway,  setting  and  resetting  curbing,  laying 
or  relaying  sidewalks  where  required,  furnishing  all  new  material 
and  performing  all  the  labor  required  for  paving  the  roadway, 
together  with  all  incidental  work  necessary  to  complete  the  whole 
in  a  proper  manner,  in  accordance  with  the  contract,  the  plans  on 
file  in  the  office  of  the  City  Engineer,  these  Specifications  and  the 
instructions  of  the  City  Engineer,  herein  referred  to  as  the  Engineer, 
or  his  authorized  agents. 

References. 

The  numbered  divisions  of  these  specifications  are  herein  desig- 
nated as  "sections,"  each  being  referred  to  by  the  number  standing 
at  its  beginning. 

The  plans  and  drawings  relating  to  this  work,  on  file  in  the 
office  of  the  City  Engineer  are  designated  as 

Authority. 

1.  Wherever,  in  these  specifications,  the  words,  the  City,  are 
used,  they  shall  be  understood  to  refer  to  the  duly  constituted 
municipal  government  of  the 'city  of 

or  its  authorized  agents,  acting  within  the  authority  specifically  con- 
ferred upon  them  by  the  said  municipal  government.* 

Wherever,  in  these  specifications,  the  words,  the  Engineer, 
shall  be  used,  they  shall  be  understood  to  refer  to  the  City  Engineer 


*In  specifications  to  be  used  in  any  particular  city  the  official  name 
of  the  city  government,  as  the  City  Council,  the  Commissioners  of 
Public  Works,  etc.,  should  be  used  instead  of  this  general  designation. 


10 

of  said  city,  or  his  deputies  or  assistants  acting  within  the  authority 
conferred  upon  them  by  the  City  Engineer. 

But  no  agent  of  the  city  shall  have  power  to  revoke,  alter, 
enlarge  or  relax  the  stipulations  or  requirements  of  these  speci- 
fications, except  in  so  far  as  such  authority  may  be  specifically  con- 
ferred in  or  by  the  specifications  themselves,  without  the  formal 
authorization  so  to  do,  'conferred  by  ordinance,  resolution  or  other 
usual  official  action  of  the  city.* 

Interpretation. 

2.  In  case  of  any  actual  or  alleged  disagreement  or  discrep- 
ancy between  the  contract,  these  specifications,  and  the  plans  for  the 
work  on  file  in  the  office  of  the  Engineer,  the  language  and   pro- 
visions of  the  contract  shall  take  precedence  and  prevail;    and  the 
Engineer   shall   determine   in   each   case   whether   the   specifications 
or  the  plans  shall  be  followed. 

Quality  of  Material  and  Work. 

3.  The  judgment  and  decision  of  the  Engineer  as  to  whether 
the  materials  supplied  and  the  work  done  under  this  contract  comply 
with  the  requirements  of  these  specifications,  shall  be  conclusive  and 
final.      No   material   shall   be   used   in   the   work   until   it  has   been 
examined  and  approved  by  the  Engineer,  or  his  authorized  agents. 
All  rejected  material  must  be  promptly  removed  from  the  work  and 
replaced    with   that   which    is   acceptable   to   the   Engineer,    and   all 
improper  or   defective   work   must  be   corrected,   and,   if   necessary, 
removed  and  reconstructed  so  as  to  comply  with  these  specifications 
and  the  instructions  of  the  Engineer. 

Inspection. 

4.  The  Engineer  may  provide  for  the  inspection,  by  assistants 
and  inspectors  under  his  direction,  of  all  materials  used  and  all  work 
done  under  this  contract.     Such  inspection  may  extend  to  all  or  any 
part  of  the  work,  and  to  the  preparation  or  manufacture  of  materials 
to  be  used,  whether  within  the  limits  of  the  work  on  the  street,  or 
at  any  other  place.     The  Engineer  and  his  inspectors  shall  have  free 
access  to  all  parts  of  the  work,  including  mines,  quarries,  manufac- 
tories, or  other  places  where  any  part  of  the  materials  to  be  used 
is  procured,  manufactured  or  prepared.     The  Contractor  shall  fur- 
nish  the   Engineer   all   information   relating   to   the   work    and   the 
material  therefor  which  the  Engineer  may  deem  necessary  or  perti- 
nent, and  with  such  samples  of  materials  as  may  be  required.     The 
Contractor  shall,  at  his  expense,  supply  inspectors  with  such  labor 
and  assistance  as  may  be  necessary  in  the  handling  of  materials  for 
proper  inspection.     Inspectors  shall  have  authority  to  reject  defective 
material  and  to  suspend  any  work  that  is  being  improperly  done, 


*Such  a  proviso  as  this  seems  proper  in  justice  to  both  the  city 
engineer  and  the  contractor;  the  former  should  not  be  held  responsible 
for  the  acts  of  his  assistants  when  they  transcend  the  authority  con- 
ferred upon  them,  and  the  latter  should  be  put  upon  his  guard  with 
reference  to  requirements  which  he  is  not  satisfied  are  sanctioned  or 
approved  by  the  city  engineer. 


11 

subject  to  the  final  decision  of  the  Engineer.  Inspectors  shall  have 
no  authority  to  permit  deviations  from,  or  to  relax  any  of  the  pro- 
visions of  these  specifications  without  the  written  permission  or 
instruction  of  the  Engineer;  nor  to  delay  the  Contractor  by  failure 
to  inspect  materials  and  work  with  reasonable  promptness. 

The  payment  of  any  compensation,  whatever  may  be  its  char- 
acter or  form,  or  the  giving  of  any  gratuity,  or  the  granting  of  any 
valuable  favor,  by  the  Contractor  to  any  inspector,  directly  or  indi- 
rectly, is  strictly  prohibited,  and  any  such  act  on  the  part  of  the 
Contractor  will  constitute  a  violation  of  these  specifications.* 

Injuries  to  Persons  and  Property. 

5.  The    Contractor    shall    be    held    alone    responsible    for    all 
injuries  to  persons,  and  for  all  damages  to  the  property  of  the  city 
or  others,  caused  by  or  resulting  from  the  negligence  of  himself, 
his  employees  or  agents,  during  the  progress  of,  or  connected  with 
the  prosecution  of  the  work,  whether  within  the  limits  of  the  work, 
or  elsewhere.     He  must  restore  all  injured  property,  including  side- 
walks, curbing,  sodding,  pipes,  conduits,  sewers  and  other  public  or 
private  property  to  a  condition  as  good  as  it  was  when  he  entered 
upon  the  work. 

Sanitary  Conveniences;  Nuisances. 

6.  The  Contractor  shall  provide  all  necessary  privy  accommo- 
dations for  the  use  of  his  employees  on  the  street,  and  shall  maintain 
the  same  in  a  clean  and  sanitary  condition.     He  shall  not  create 
nor  permit  any  nuisance  to  the  public  or  to  residents  in  the  vicinity 
of  the  work. 

Public  Convenience. 

7.  No  material,  or  other  obstruction  shall  be  placed  within  five 
feet  of  fire  hydrants,  which  must  be  at  all  times  readily  accessible 
to  the  Fire  Department. 

During  the  progress  of  the  work  the  convenience  of  the  public 
and  of  the  residents  along  the  street  must  be  provided  for  as  far  as 
practicable.  Convenient  access  to  driveways,  houses  and  buildings 
along  the  street  must  be  maintained  wherever  possible.  Temporary 
approaches  to  and  crossings  of  intersecting  streets  and  sidewalks 
must  be  provided  and  kept  in  good  condition,  wherever  practicable. 
Barriers,  Lights,  Watchmen. 

8.  The   Contractor   shall   provide   and   maintain   such   fences, 
barriers,  "street  closed"  signs,  red  lights,  and  watchmen  as  may  be 
necessary  to   prevent  avoidable   accidents  to  residents   and   to   the 
public. 


*It  may  be  objected  that  this  requirement  is  unusual  and  unneces- 
sary, since  such  practices  are  recognized  as  wrong,  and  as  presumptive 
of  fraud  and  malpractice  on  the  part  both  of  the  contractor  and  the 
Inspector.  It  cannot,  however,  be  denied  that  in  many  cities  such  means 
are  employed  by  contractors  to  unduly  influence  the  action  of  inspectors 
and  that  not  infrequently  the  latter  not  only  accept,  but  persistently 
demand,  valuable  considerations  from  the  contractor.  Silence  of  the 
specifications  on  this  point  cannot,  of  course,  be  construed  into  consent, 
but  there  is  no  good  reason  for  the  silence.  There  should  be  left  no 
excuse  for  misconception  of  the  position  of  the  city  or  of  the  engineer 
upon  this  point.  '  . 


12 

Disorderly  Employees. 

9.  Disorderly,  intemperate,  or  incompetent  persons  must  not 
be   employed,    retained,    or   allowed    upon   the   work.      Foremen    or 
workmen  who  neglect  or  refuse  to  comply  with  the  instructions  of 
the  Engineer,  shall,  at  his  request,  be  promptly  discharged,  and  shall 
not  thereafter  be  re-employed  without  his  consent. 

Order  and  Progress  of  Doing  Work. 

10.  The  work  under  this  contract  shall   be  prosecuted   at  as 
many  different  points,  at  such  times,  and  in  such  sections  along  the 
line  of  the  work,  and  with  such  forces  as  the  Engineer  may  from 
time  to  time  deem  necessary,  and  direct,  to  secure  its  completion 
within   the  contract  time.      Not   more   than   one   thousand    (1,000) 
linear  feet  of  the  street  shall  be  torn  up,  obstructed  or  closed  to 
travel  at  any  one  time  without  the  written  permission  of  the  Engi- 
neer.    Completed  portions  of  the  pavement  shall  be  opened  to  travel 
as  directed  by  the  Engineer,  but  such  opening  shall  not  be  construed 
as  an  acceptance  by  the  City  of  the  work  done.     Where  thus  opened 
to  public  travel   by  the  direction   of  the  Engineer,   the   Contractor 
will  not  be  held  responsible  for  injuries  to  the  work  caused  by  such 
travel  or  public  use,   pending  the  final   completion  and   acceptance 
of  the  whole  work. 

Measurement  and  Estimates. 

11.  Final  estimates  will  be  based  upon  the  actual  quantities 
of  completed  and  accepted  work,  customary  or  conventional  methods 
of  measurement  and  computation  to  the  contrary  notwithstanding. 

Grade  and  Contour  of  Pavement. 

12.  Roadway  pavements  shall  be  laid  to  such  grades,  crown 
and  contour  of  surface  as  the  plans  may  show  or  the  Engineer  may 
direct,   and   the  surface  of  the  completed   pavement   shall   conform 
accurately  to  such  grades,  crown  and  contour.     The  designed  surface 
of   the   completed   pavement  shall   be   considered    as   the   datum    or 
plane  of  reference  in  fixing  the  location  or  level  of  the  sub-grade, 
of  the  pavement  foundation,  and  of  structures  connected  therewith. 
It  will  be  hereafter  referred  to  in  these  specifications  as  "The  pave- 
ment datum." 

City  Monuments  or  Stakes. 

13.  The  Contractor  must  carefully  protect  from  disturbance  or 
injury  all  city  monuments,  stakes  and   benchmarks,   and   shall   not 
excavate  nearer  than  five  feet  to  any  of  them  without  the  permission 
of  the  Engineer;    or  until   they  have   been  removed,   witnessed,   or 
otherwise  disposed  of  by  the  Engineer. 

Old  Material. 

14.  All   material  or  structures  removed   from   the  street  and 
not  required  for  the  new  construction,  but  which  the  city  may  desire 
to  reserve,  shall  be  delivered  and  neatly  piled  up  in  a  corporation 
yard  or  elsewhere,  by  the  Contractor,  as  the  Engineer  may  direct. 
Such  reserved  material  shall  be  considered  in  the  custody  of  the 


13 

Contractor  until  delivered  at  the  place  designated,  and  he  will  be 
held  responsible  for  its  care  and  protection,  and  must  make  good 
any  losses  occasioned  by  damage,  theft,  or  misappropriation  while 
it  is  on  the  street  or  en  route  to  the  place  of  storage.  If  the  Con- 
tractor shall  be  required  to  haul  such  reserved  material  more  than 
one-half  mile,  he  shall  be  paid  a  reasonable  price,  to  be  agreed  upon 
in  advance,  for  the  haul  exceeding  that  distance. 

Material  taken  from  the  work  which  is  to  be  used  in  the  new 
construction  shall  be  compactly  piled  where  it  will  least  obstruct 
the  sidewalks  or  adjoining  sections  of  the  street,  and  properly 
protected  by  the  Contractor  until  it  is  required  for  use. 

All  old  material  removed  from  the  work,  including  the  material 
excavated  in  preparing  the  sub-grade,  not  reserved  by  the  City  nor 
to  be  used  again  in  the  work,  shall  belong  to  the  Contractor  and 
must  be  removed  by  him  from  the  street  as  promptly  as  possible. 
It  must  not  be  placed  on  the  sidewalks  or  adjacent  streets,  nor  on 
any  other  street  or  property  belonging  to  the  City,  nor  on  the  prop- 
erty of  private  owners,  without  the  written  consent  of  the  Engineer, 
or  the  owner  of  the  property. 

Storage  of  New  Material. 

15.  The   material    for    construction    when    brought   upon   the 
street  shall  be  neatly  piled  so  as  to  cause  as  little  obstruction  to 
travel  as  possible,  and  so  that  it  may  be  conveniently  inspected. 

Rebuilding  and  Adjusting  Street  Structures. 

16.  Catch  basins,  manhole,  sewer  and  water  frames  and  covers, 
sewer  inlets,  water  pipes  and  other  conduits,  belonging  to  the  City 
and  within  the  limits  of  the  work,  shall,  if  necessary,  be  reset  to 
the  new  lines  and  grades  of  the  street  and  for  this  purpose  good 
brick   masonry  of  the  original   thickness,    laid   in   Portland   cement 
mortar  shall  be  used.     Great  care  must  be  taken  to  set  all  such 
structures  as  project  through  the  pavement  exactly  to  the  grade  and 
contour  of  the  new  street  surface,  and  any  defects  in  the  conformity 
of  such  structures  to  the  pavement  datum,  discovered  at  the  time, 
or  during  the  progress  of  the  work,  or  during  the  guaranty  period, 
stipulated    in   Sec.    108,    shall    be    promptly    remedied    by   the    Con- 
tractor. 

Noiseless  Manhole  Covers. 

17.  Asphalt-filled   noiseless   covers,    complete,    for   water   and 
sewer  manholes,  of  approved  design,  shall  be  furnished  and  set  by 
the  Contractor  wherever  directed  by  the  Engineer.     They  shall  be 
made  according  to  general  plans  and  details  furnished  by  the  Engi- 
neer, and  of  such  dimensions  as  to  properly  fit  their  frames. 

Clean  Sidewalks. 

18.  During  the  progress  of  the  work,  the  sidewalks  and  por- 
tions of  the  street  adjoining  the  work,  or  in  its  vicinity,  must  not  be 
obstructed  or  littered  more  than  may  be  absolutely  necessary,  and 
the  adjacent  sidewalks  must  be  kept  clean. 


14 

Final  Cleaning  Up. 

19.  Immediately   after    the    completion   of   the    work    or   any 
consecutive  portion  of  it,  the  Contractor  shall  remove  from  it  all 
unused  material,  refuse  and  dirt  placed  by  him  on,  or  in  the  vicinity 
of   the   work,    or    resulting    from    its    prosecution,    and    restore    the 
street  to  a  condition  as  clean  as  before  the  work  was  begun;  and  the 
new  pavement  shall  be  properly  cleaned. 

Incidental  Work  at  Contractor's  Expense. 

20.  All  the  work  to  be  done  by  the  Contractor,  specified  and 
enumerated  in  Sections  3,  4,  5,  6,  7,  8,  10,  11,  12,  13,  14,  15,  16,  17, 
18  and  19,  as  well  as  any  minor  details  of  work  not  specifically  men- 
tioned in  the  specifications,  but  obviously  necessary  for  the  proper 
completion  of  the  work,  shall  be  considered  as  incidental,  and  as 
being  a  part  of  and  included  with  the  work  for  which  prices  are 
named  in  the  contract.     The  Contractor  will  not  be  entitled  to  any 
extra  or  additional  compensation  therefor. 

Extra  Work. 

21.  The    City    may    require    the    Contractor    to    furnish    such 
additional  materials  and  to  do  such  additional  work,  not  provided 
for  in  the  contract  and  these  specifications,  but  which  may  be  found 
necessary  or  pertinent  to  the  proper  prosecution  and  completion  of 
the  work  embraced  in  the  contract,  at  prices  to  be  agreed  upon  in 
writing,  in  advance.     But  no  work  other  than  that  included  in  the 
contract  and  these  specifications  and  which  is  covered  by  and  to  be 
paid  for  at  the  prices  named  in  the  contract,  shall  be  done  by  the 
Contractor  except  upon  a  written  order  from  the  Engineer.     In  the 
absence  of  such  written  order  from  the  Engineer  the  Contractor  will 
not  be  entitled  to  payment  for  any  such  additional  or  extra  work. 

Curbing  to  be  Completed  in  Advance. 

22.  The   setting   of   all   new   curbing   and   guttering   and    the 
redressing,   resetting  or   readjustment  of  all   old   curbing   must   be 
completed  at  least  100  feet  in  advance  of  the  construction  of  the 
street  foundation. 

Preparing  the  Sub-Grade. 

23.  The  whole  area  to  be  occupied  by  the  pavement  and  its 
foundation  shall  be  excavated  to  a  sub-grade  at  such  a  depth  that 

after  being  compacted  by  the  roller,  the  surface  will  be 

inches  below  the  pavement  datum,  and  truly  parallel  thereto.     In 
excavating,  the  earth  must  not  be  disturbed  below  the  sub-grade. 
Plowing   will    not   be   permitted    where   the    depth   of   earth   to    be 
removed  is  less  than  six  (6)   inches,  and  in  no  case  must  the  plow 
be  allowed  to  penetrate  to  within  less  than  one  inch  of  the  sub-grade. 
Places  that  are  found  to  be  loose,  or  soft,  or  composed  of  unsuitable 
material,  below  sub-grade,  must  be  dug  out  and  refilled  with  sand, 
or  other  material  as  good  as  the  average  of  that  found  on  the  street. 
After  the  excavation  is  completed  and  the  surface  neatly  trimmed, 
the  whole  area  shall  be  well  compacted   by  rolling   with   a   roller 


weighing  not  less  than  five  tons.  Areas  inaccessible  to  the  roller 
shall  be  rammed  until  they  are  as  well  compacted  as  the  rolled  sur- 
face. When  the  rolling  is  completed  the  surface  must  be  nowhere 
more  than  three-fourths  inch  below,  nor  more  than  three-eighths 
inch  above  the  true  sub-grade.  If,  after  the  rolling  is  completed  and 
before  the  pavement  foundation  is  laid,  the  surface  shall  become 
disturbed  in  any  way,  it  must  be  replaced  and  properly  compacted. 

Where  the  natural  surface  of  the  ground  shall  be  below  the  sub- 
grade,  or  shall  become  so  by  the  removal  of  old  pavement  or  other 
structures,  it  must  be  filled  to  the  sub-grade  in  layers  not  exceeding 
five  inches  in  depth,  and  each  layer  shall  be  thoroughly  rolled  or 
rammed  before  the  next  layer  is  placed  upon  it,  and  when  the  filling 
is  completed  the  filled  area  must  be  properly  trimmed  and  com- 
pacted by  rolling  or  ramming  to  the  true  sub-grade,  as  in  excavation. 
The  material  excavated  from  the  street  may  be  used  for  such  filling, 
provided  it  be  of  suitable  quality.  Where  it  cannot  be  thus  procured 
from  the  street  it  must  be  obtained  by  the  Contractor  elsewhere,  in 
which  case  the  actual  quantity  so  obtained,  measured  after  it  is  com- 
pacted in  the  street,  will  be  paid  for  at  the  contract  price  for  "earth 
filling."  The  price  bid  for  "earth  excavation"  will  be  paid  for  all 
material  excavated  above  the  sub-grade,  measured  in  place  on  the 
street,  which  price  includes  the  cost  of  disposing  of  the  excavated 
material,  whether  as  waste  or  filling,  and  of  trimming  and  rolling 
or  ramming  the  sub-grade,  and  of  making  it  ready  for  the  pavement 
foundation. 

Where  the  soil  composing  the  sub-foundation  is  found  to  be  wet 
or  "springy,"  a  system  of  soft  tile  drains,  discharging  into  the  street 
drainage  system,  shall  be  constructed  by  the  Contractor,  as  directed 
by  the  Engineer.  The  tile  shall  be  laid  in  trenches  about  one  foot 
wide  and  from  one  to  two  feet  deep.  After  the  tile  is  in  place  the 
trenches  shall  be  filled  with  compacted  crushed  stone  or  gravel.  The 
tile  will  be  paid  for  at  the  contract  prices  for  the  same,  which  shall 
include  the  cost  of  excavating  and  filling  the  trenches. 

PAVEMENT  FOUNDATION. 

2*.  Pavement  foundation  shall  consist  of  hydraulic  concrete, 
or  of  old  pavement  stonp  relaid,  or  of  broken  stone  or  gravel,  as 
may  be  herein  specified,  constructed  upon  the  sub-grade.* 


*In  the  great  majority  of  cases  the  most  satisfactory  and,  in  the 
end,  the  most  economical  foundation  for  a  pavement  is  hydraulic 
cement  concrete.  Old  paving  block  foundation,  if  constructed  as  speci- 
fied in  Sect.  36,  will  give  results  equally  as  satisfactory,  but  if  a  fair 
market  exists  for  the  blocks  taken  up  from  the  street,  it  will  usually 
be  found  more  economical  to  sell  them  and  construct  a  concrete  foun- 
dation for  the  new  pavement.  Broken  stone  or  gravel  foundations  may 
serve  the  purpose  fairly  well  upon  a  street  of  light  travel,  but  it  should 
never  be  used  on  streets  of  considerable  or  heavy  travel.  Its  lower 
first  cost  is  the  only  thing  in  its  favor,  but  this  will,  in  nearly  every 
case,  be  more  than  offset  by  the  better  service  and  greater  durability 
of  the  pavement,  even  on  streets  of  light  travel,  if  laid  upon  an 
adequate  hydraulic  concrete  foundation.  Proper  repairs  to  pavement 
surfaces  cut  into  for  pipe  work,  etc.,  are  difficult  to  make  and  hardly 
ever  satisfactory  ov'er  broken  stone  foundation  for  the  reason  that  the 
lack  of  cohesion  in  the  material  allows  it  to  loosen  or  crumble  away 


16 

CONCRETE  FOUNDATION. 

Concrete. 

25.  Concrete   shall    be    composed    of    Portland    cement,    sand, 
broken  stone  and  water. 

Portland  Cement.* 

26.  Portland  cement  shall  be  denned  as  the  pulverized  product 
resulting   from   the   calcination   to   incipient   fusion  of  an   intimate 
mixture  of  properly  proportioned  argillaceous  and  calcareous  mater- 
ials, and  to  which  no  addition  greater  than  three  per  cent,  has  been 
made  subsequent  to  calcination. 

Specific  Gravity.  The  specific  gravity  of  the  dry  cement  at  a 
temperature  of  two  hundred  and  twelve  (212)  degrees  P.  shall  not 
be  less  than  3.10. 

Fineness.  It  shall  be  pulverized  to  such  fineness  that  not  more 
than  eight  (8)  per  cent,  shall  fail  to  pass  a  number  one  hundred 
(100)  sieve  and  not  more  than  twenty-five  (25)  per  cent,  shall  fail 
to  pass  a  number  two  hundred  (200)  sieve. 

Time  of  Setting.  At  the  temperature  of  sixty  (60)  degrees  F. 
mortar  made  of  neat  cement  shall  not  begin  to  set  in  less  than  thirty 

from  under  the  edge  of  the  pavement  surface,  and  it  is  difficult  to 
restore  it  to  its  original  solidity  and  strength.  The  first  cost  saved  by 
its  use  is  usually  not  great;  for  whenever  its  use  would  be  permissible 
at  all,  a  comparatively  thin  and  lean  concrete  would  give  better  results, 
at  a  very  slight  increase  in  cost.  To  illustrate:  On  a  suburban  street 
with  light  travel  a  concrete  foundation  four  inches  in  thickness,  the 
concrete  made  with  Portland  cement  in  the  ratio  of  1  cement,  4  sand 
and  8  stone,  would  be  stronger  and  in  every  way  better  than  a  foun- 
dation eight  inches  in  depth  of  broken  stone.  At  the  usual  prices  of 
materials  and  labor,  the  former  may  cost  about  $0.46  per  sq.  yd.,  and 
the  latter  about  $0.40  per  sq.  yd.;  but  for  the  latter  there  would  be 
required  1-9  cu.  yd.  more  sub- foundation  excavation,  worth  about  four 
cents,  so  that  the  equivalent  cost  would  be  $0.44  per  sq.  yd.  The 
difference,  two  cents  per  sq.  yd.,  is  insignificant  when  compared  with 
the  greater  value,  better  service,  and  greater  durability  of  a  pavement 
on  the  concrete  foundation.  It  is  sometimes  held  that  the  broken  stone 
foundation  provides  necessary  sub-drainage.  But  all  the  standard 
pavements  are.  or  soon  become,  impermeable  to  water  from  the  surface, 
and  seepage  from  the  sub-foundation  can  be  better  taken  care  of  by 
the  sub-drainage  specified  in  Sect.  23,  which  should  usually  cost  not 
more  than  five  cents  per  square  yard  of  the  pavement;  and  if  drainage 
be  required,  these  sub-drains  should  be  used  even  with  the  broken  stone 
foundation. 

The  practice  of  laying  pavement  surfaces,  particularly  those  of 
asphalt,  upon  a  foundation  of  old  stone  blocks,  carelessly  reset,  with 
the  joints  unfilled  with  mortar,  (common  in  a  few  cities)  is  all  wrong 
and  should  never  be  resorted  to.  The  integrity  and  durability  of  an 
asphalt  pavement  depends  largely  upon  the  strength  and  rigidity  of 
its  foundation;  to  lay  an  asphalt  surface,  however  good,  over  such  an 
old  block  foundation,  is  an  inexcusable  waste  of  money. 

Old  stone  block  and  cobble-stone  pavements  that  have  become 
solidified  in  place  by  long  travel  over  them,  make  a  good  foundation 
for  asphalt  or  other  pavements,  provided  they  can  be  utilized  without 
taking  up  or  disturbing  the  old  pavement;  but  such  cases  occur  so 
rarely  that  they  have  not  been  considered  in  these  specifications. 

A  thoroughly  consolidated  old  McAdam  pavement,  if  not  worn  too 
thin,  also  makes  a  very  satisfactory  pavement  foundation  if  it  can  be 
used  undisturbed,  or  by  simply  trimming  off  the  high  points. 

Low  places,  otherwise  satisfactory  in  old  pavements  to  be  used 
for  foundation,  may  be  brought  to  the  proper  elevation  with  hydraulic 
concrete.  "Binder'  material  is  usually  specified  for  this  purpose  in 
foundations  for  asphalt  pavements,  but  hydraulic  concrete  is  both 
better  and  cheaper. 

*The  specifications  for  Portland  cement  here  given  are  practically 
those  adopted  by  the  "American  Society  for  Testing  Materials." 

Natural  Cement.  While  these  specifications  uniformly  refer  to 
the  use  of  Portland  cement,  it  is  not  intended  to  convey  the  idea  that 
natural  cement  concrete  is  not  suitable  for  pavement  foundations;  on 
the  contrary,  it  may  be  used  with  entire  confidence,  as  the  experience 
in  a  large  number  of  cities  has  proven  beyond  question.  Whether 
Portland  or  natural  cement  shall  be  used  is  usually  a  question  of 
relative  cost.  At  the  present  very  low  prices  of  Portland  cement  in 


17 

(30)  minutes,  nor  set  hard  in  less  than  one  hour,  but  must  set  hard 
within  ten  (10)  hours. 

Strength.  When  thoroughly  mixed  dry  with  clean,  sharp,  mod- 
erately coarse  sand,  in  the  ratio  by  weight  of  one  part  cement  to 
three  parts  of  sand,  and  then  made  into  stiff  mortar,  briquets 
made  from  this  mortar  and  exposed  for  one  day  to  moist  air  and 
immersed  in  water  for  the  balance  of  the  periods  named  below,  shall 
develop  a  tensile  strength  per  square  inch  not  less  than  the  follow- 
ing: 

In  seven  days 175  pounds. 

In  twenty-eight  days 250  pounds. 

Constancy  of  Volume.  When  subjected  to  standard  tests  for 
constancy  of  volume,  the  cement  shall  show  no  tendency  to  swell  or 
crack. 

Composition.  The  cement  shall  not  contain  more  than  one  and 
three-fourths  (1.75)  per  cent,  of  anhydrous  sulphuric  acid,  nor  more 
than  four  (4)  per  cent,  of  magnesia. 

Tests.  Cement  tests  shall  be  conducted  in  accordance  with  the 
methods  recommended  by  the  "Committee  on  Uniform  Tests  of 
Cement"  of  the  American  Society  of  Civil  Engineers. 

Conditions.  All  cement  shall  be  supplied  in  original  packages 
with  the  brand  of  the  manufacturer  marked  on  each  package.  It 
shall  be  protected  during  transportation  from  rain  and  moisture. 
It  shall  be  delivered  upon  the  work  at  least  ten  (10)  days  (exclus- 
ive of  Sundays  and  holidays)  before  it  is  to  be  used,  in  order  to 
allow  of  proper  inspection,  and  the  contractor  shall  furnish  all 
necessary  facilities  for  such  inspection.  Brands  of  cement  without 
established  good  reputation,  or  not  heretofore  used  in  the  City  of 

may  be  rejected;  or  they  will  be  accepted 

only  after  they  satisfactorily  pass  the  28-day  test.     Rejected  cement 

must  be  at  once  removed  from  the  street. 

Sand. 

27.  Sand  for  concrete  shall  be  composed  of  grains  not  softer 
than  hard  limestone.  It  shall  be  moderately  coarse  and  preferably 
made  up  of  grains  of  varying  size  producing  a  mass  with  low  per- 
centage of  voids.  It  shall  not  contain,  in  all,  more  than  five  (5) 
per  cent,  by  volume  of  clay,  loam,  mica  scales,  silt,  or  other  objec- 
tionable inorganic  matter,  nor  more  than  one  (1)  per  cent,  of 
organic  matter. 

many  cities,  more  strength  in  pavement  foundations  can  usually  be 
obtained  per  dollar  expended  for  cement,  from  Portland  than  from 
natural  cement.  The  specifications  for  natural  cement,  as  adopted  by 
the  American  Society  for  Testing  Materials  differ  from  those  for  Port- 
land cement  in  the  following  particulars: 

The  specific  gravity  shall  not  be  less  than  2.8. 

Fineness.  The  residue  left  on  a  No.  100  sieve  shall  not  exceed 
10  per  cent.,  and  on  a  No.  200  sieve  shall  not  exceed  30  per  cent. 

Setting.     It  shall  not  begin  to  set  in  less  than  ten  minutes,  nor  set 
hard  in  less  than  thirty  minutes;  but  shall  set  hard  within  three  hours. 
Tensile  Strength    (per  sq.   in.). 

Neat.     24  hours  in  moist  air 50  to  100  Ibs. 

7  days  (1  day  in  air,  6  days  in  water) 100  to  200  Ibs. 

28  days  (1  day  in  air,  27  days  in  water) 200  to  300  Ibs. 

1  part  cement,  3  parts  sand. 

7  days.   (1  day  in  air,  6  days  in  water) 25  to     75  Ibs. 

28  days.    (1  day  in  air,  27  days  in  water) 75  to  150  Ibs. 

Soundness.  Standard  pats  kept  in  air  and  in  water  should  remain 
firm  and  hard  and  show  no  signs  of  cracking  or  disintegration. 


18 

Broken  Stone. 

28.  Broken   stone   for   concrete   shall   be   of   hard   and   sound 
limestone    or    other    stone    equally    hard    and    durable,    broken    to 
a    roughly    cubical    form.      It    shall    be    screened    through    efficient 
revolving  screens,  and  only  such  fragments  as  have  passed  through 
circular  screen  openings  two  and  one-half  (2^)  inches  in  diameter, 
shall    be    used.      If   the   crushed    dust    and    fine    fragments    be    not 
screened  out,  the  stone  must  be  so  handled  that  the  fine  material 
will   be  evenly  distributed  through   the  mass  when  it  reaches  the 
concrete  platform  or  mixer.* 

Water. 

29.  Water   used   for   concrete  shall  be   fresh,   and   reasonably 
clear. 

Care  and  Handling  of  Concrete  Material. 

30.  Cement  must  not  be  allowed  to  become  wet  or  damp.     It 
shall  be  stored  until  used,  whether  in  storehouses  or  on  the  street, 
so  that  no  part  of  the  packages  shall  be  nearer  than  four  (4)  inches 
to  the  ground  or  pavement,  and  shall  be  effectually  covered  so  that 
rain  cannot  reach  it.     Sand  and  stone,  if  stored  on  the  street,  shall 
be   on   lumber   floors. t      The   stone   shall   be   thoroughly   wetted    a 
sufficient   time   before   being   placed   in   the   concrete   to   allow   any 
surplus  water  to  drain  away,  but  shall  remain  moist  when  it  reaches 
the  concrete  platform  or  mixer. 

Ratio  of  Concrete  Materials. 

31.  Concrete  will  be  composed  of  one  part  Portland  cement 

parts  of  sand  and parts 

of  broken  stone,  and  the  proper  quantity  of  water,  all  measured  by 
volume.?     The  unit  of  measurement  shall  be  the  barrel  of  cement 
which  shall  be  considered  as  containing  four    (4)    cubic  feet.     The 
materials  shall   each   be  measured   in   such  manner   and   with   such 
accuracy  that  the  quantities  used  will  not  vary  more  than  seven  (7) 
per  cent,  from  the  quantities  required  in  the  ratio  named  above  for 
each  batch  of  concrete. 

*The  frequent  requirement  that  the  fine  material  shall  be  screened 
out,  is  not  necessary  or  advisable.  Experiments  and  experience  have 
shown  conclusively  that  unless  an  unusual  amount  of  fine  material  and 
"dust"  be  present,  or  unless  this  fine  material  be  allowed  to  separate 
and  aggregate  in  masses  by  itself,  the  resulting  concrete  is  improved 
rather  than  deteriorated  by  its  presence. 

Where  there  is  an  unusual  excess  of  "dust"  in  the  crushed  stone, 
the  quantity  of  sand  used  in  the  concrete  should  be  decreased  accord- 
ingly. 

fMany  specifications  do  not  require  this  and  in  a  number  of  cities 
where  the  specifications  do  require  it,  contractors  habitually  neglect 
to  comply.  When  stone  and  sand  are  deposited  directly  upon  the  earth, 
it  is  very  difficult  to  avoid  taking  up  earth  and  mud  with  the  materials, 
particularly  when  the  street  is  wet  and  muddy.  Lumps  of  soil  and 
debris  unquestionably  injure  the  concrete.  The  cost  of  providing  a 
lumber  floor  is  comparatively  small,  as  the  plank  may  be  used  over  and 
over  again.  Specifications  should,  therefore,  contain  this  requirement 
and  it  should  be  enforced. 

tThe  ratios  of  the  materials  may  appropriately  be  varied  with  the 
strength  and  soundness  of  the  sub-foundation,  the  amount  of  travel 
on  the  street,  and  with  the  thickness  of  foundation  it  is  proposed  to 
use.  Where  good  materials  are  used  and  the  work  is  properly  done, 
a  1:3:5  concrete  six  inches  thick  is  sufficient  for  streets  of  the  heaviest 
travel.  For  streets  of  light  travel  a  1:5:9  concrete  will  usually  give 
entirely  satisfactory  results.  The  most  economical  thickness  for  a 
concrete  foundation  is  an  important  consideration.  The  strength  of 
concrete  may  be  said  to  increase,  within  usual  limits  of  practice,  with 
the  ratio  of  cement  in  it.  The  strength  of  concrete  beams  or  slabs 


19 

Mixing  Concrete. 

32.  If  mixed  by  hand,  concrete  shall  be  mixed  on  platforms 
of  iron  or  wood  of  sufficient  size  to  admit  of  proper  manipulation 
of  the  concrete.     The  sand  shall  be  first  spread  evenly  over  the  plat- 
form and  the  cement  evenly  distributed  over  the  sand.     These  two 
materials  shall  then  be  mixed  dry  until  a  uniform  and  homogeneous 
mixture  is  secured.     Sufficient  water  shall  then  be  added  and  the 
mixing    resumed    and    continued    until    a    mortar    of    uniform    con- 
sistency and  texture  is  produced  and  distributed  in  an  even  layer 
over  the  platform.     The  stone  shall  then  be  distributed  over  the 
mortar  and  mixed  therewith  until  the  mortar  is  evenly  distributed 
through  the  mass  and  every  fragment  of  stone  is  well  coated  with 
mortar,  sufficient  additional  water  being  added  as  the  mixing  pro- 
gresses to  produce  a  rather  wet,  but  not  sloppy,  concrete.*     Machine 
mixing  of  concrete  will  be   preferred,   provided   the   machine   used 
secures  equal  accuracy  in  the  ratios  of   materials   and   equally  as 
good  mixing  as  prescribed  above  for  hand-mixing.     Machine-mixed 
concrete  must  be  delivered  from  the  machine  upon  a  wood  or  metal 
platform  and  be  thence  shovelled  into  place  on  the  street. 
Placing  the  Concrete. 

33.  Concrete  shall  be  placed  on  the  sub-grade  in  such  a  man- 
ner as  to  prevent  as  far  as  possible  the  separation  of  the  mortar 
from  the  stone.     It  shall  be  evenly  distributed  in  a  single  horizontal 
layer  of  such  depth  that,  after  ramming,  it  will  be  not  less  than 

inches  thick.  |     Immediately  after  being  so  placed  it 

shall  be  well  rammed  until  a  compact  mass  is  produced  with  its 

upper   surface   parallel   to   and inches   below    the 

pavement  datum.     Depressions  that  may  appear  during  the  ramming 

increases  in  the  ratio  of  the  square  of  their  depth.  To  secure  a  required 
amount  of  strength  in  a  pavement  foundation,  we  may  therefore  vary 
the  richness  of  the  concrete  and  the  depth  of  the  foundation  so  as  to 
secure  the  requisite  'strength  at  the  least  total  cost  of  materials  and 
labor.  This  will  be  influenced  by  the  cost  of  materials  and  labor  in 
each  particular  locality. 

Within  certain  workable  limits  there  is  no  reason  why  the  same 
principles  of  proportioning  the  strength  of  a  pavement  foundation  to 
the  work  required  of  it  should  not  be  applied  as  are  employed  in 
designing  other  engineering  structures. 

The  practice,  usual  in  many  cities,  of  adopting  general  specifi- 
cations requiring  a  standard  thickness  of  foundation  and  composition 
of  concrete,  and  applying  these  to  all  streets,  regardless  of  the  quan- 
tity and  character  of  travel  which  the  pavement  is  expected  to  carry, 
is  illogical  and  often  very  wasteful.  If  such  a  standard  foundation 
is  sufficient  for  the  streets  of  heaviest  travel,  it  is  obviously  a  sheer 
waste  of  money  to  use  it  on  the  suburban  streets  carrying  the  lightest 
travel.  It  is  therefore  better  in  preparing  standard  specifications  for 
pavement  in  any  city  to  leave  blanks  for  the  ratios  of  the  concrete  and 
for  the  thickness  of  the  foundation,  to  be  filled  in,  in  each  individual 
case,  as  the  judgment  of  the  engineer  may  dictate. 

While  it  is  important  that  the  foundation  of  any  pavement  shall 
be  adequate,  it  is  inexcusable  to  waste  money  in  providing  superfluous 
strength.  For  the  great  majority  of  suburban  streets,  carrying  bu. 
little  except  the  local  travel,  a  foundation  four  inches  thick  made  of 
good  Portland  cement  concrete  in  the  ratios  of  1:4:8  will  prove  entirely 
satisfactory.  Hundreds  of  such  streets  paved  over  a  foundation  of 
that  thickness,  made  of  natural  cement  concrete  in  the  ratios  of  1:2:4 
can  be  cited  where  the  foundation  has  proved  entirely  satisfactory. 

The  character  and  firmness  of  the  sub-foundation  must,  of  course, 
be  taken  into  consideration  in  designing  the  foundation. 

*The  routine  here  described  produces  better  concrete  with  less 
expenditure  of  labor,  than  the  one  often  followed  of  putting  all  the 
dry  materials  on  the  concrete  board  before  any  mixing  is  begun.  The 
writer  has  proved  this  from  actual  records  covering  a  large  quantity 
of  work. 

tSee  foot-note   (J),  page  18. 


20 

may  be  filled  with  concrete  of  the  same  composition  as  used  for  the 
foundation,   except  that   smaller-sized   stone  shall  be  used;    mortar 
alone  must  not  be  used  for  this  purpose,  nor  shall  the  upper  surface 
of  the  concrete  be  plastered  with  mortar.* 
Setting  of  Concrete. 

34.  After    the   concrete   is    completed    it   shall    remain    undis- 
turbed until  it  be  firmly  set.     The  time  allowed  for  setting  shall  not 
be  less  than  five  days,  and  as  much  longer  as,  in  the  judgment  of  the 
Engineer,  may  be  necessary,  depending  upon  the  temperature  of  the 
weather  and  the  setting  qualities  of  the  cement.     During  this  period 
no  hauling  or  traveling  over  the  concrete  must  be  permitted  unless 
its   surface   be  first   protected   by   a   covering   of   plank.      The   Con- 
tractor shall,   if  necessary,  keep  the  concrete   moist  by  wetting   it, 
with  hose,  or  otherwise,  until  twenty-four    (24)    hours  before  it  is 
to  be  covered  with  the  pavement  surface. 

Measurement  of  Concrete. 

35.  Concrete  will  be  measured  and  computed  in  cubic  yards 
as    found   completed   on   the   street,    the   thickness   being   taken   as 
inches.      The    contract    price    for    concrete    foun- 
dation covers  the  cost  of  providing  all  the  materials  required,  mak- 
ing, placing  and  ramming  the  concrete,  and  keeping  it  moist  for  the 
necessary  period. 

FOUNDATION  OF  OLD  PAVING  STONE. 

36.  Foundations    made   of   old    stone   paving   blocks    shall    be 
constructed  as  follows: 

Upon  the  sub-grade  prepared  as  specified  in  Section  23,  shall 
be  spread  a  layer  of  good  sand  to  an  even  depth  of  one  and  one-half 
(1%)  inches.  The  paving  blocks,  whether  taken  up  from  the  street 
to  be  paved,  or  brought  from  other  streets  or  storage  yards,  shall  be 
cleaned  of  all  adhering  earth,  dirt  and  street  refuse.  The  blocks 
shall  then  be  set  on  the  bed  of  sand,  on  edge,  perpendicular  to  the 
grade,  with  their  long  dimension  at  right  angles  to  the  line  of  the 
street,  in  courses  composed  of  stones  of  the  same  width,  extending 
entirely  across  and  at  right  angles  to  the  axis  of  the  street.  Stones 
in  adjoining  courses  shall  break  joint  at  least  two  inches.  Joints 
between  courses  or  stones,  or  along  the  curbstones,  shall  not  exceed 
one  inch  in  width.  The  stone  shall  be  fitted  closely  around  man- 
holes or  other  structures  in  the  street.  The  stones  shall  be  so  set 
in  the  bed  of  sand  that  after  being  rammed  as  hereafter  specified, 
their  tops  shall  be  at  the  proper  grade.  In  street  intersections  the 
courses  shall  be  laid  at  an  angle  of  forty-five  (45)  degrees  with  the 
line  of  the  street  if  the  Engineer  shall  so  direct.  After  being  thus 
set  in  place  the  stone  shall  be  rammed  with  paving  rammers  having 
wooden  faces  and  weighing  not  less  than  thirty  (30)  pounds,  so  as 

*The  objections  to  using"  mortar  for  plastering  over  the  concrete 
are:  that  it  is  more  costly  than  concrete;  that  the  two  materials  may, 
under  certain  conditions,  separate  and  the  thin  mortar  surface  break 
up  under  travel;  that,  if  permitted,  the  mortar  may  be  used  to  cover  up 
defective  concrete,  and  that  in  the  case  of  ashpalt  pavements  the  pave- 
ment surface  is  more  likely  to  "shift"  on  the  smooth  surface  of  the 
mortar  than  on  the  rough  surface  of  the  concrete. 


21 

to  force  each  stone  to  a  good  bearing  in  the  sand  below,  and  to 

bring  its  top  to  a  uniform  grade,  parallel  to  and 

inches  below  the  pavement  datum.  No  stone  shall  project  more 
than  one-fourth  ( ^4 )  inch  above  the  proper  grade,  and  stones  whose 
tops,  after  ramming,  are  more  than  three-quarters  ( % )  inch  below 
such  grade,  shall  be  raised,  additional  sand  placed  under  them,  and 
reset  and  re-rammed  to  the  proper  grade  and  bearing.  After  the 
ramming  shall  have  been  completed,  the  joints  between  the  stones 
shall  be  filled  with  mortar.  The  mortar  shall  be  composed  of  Port- 
land cement  and  sand,  complying  with  the  specifications  for  these 
materials  in  Sections  26  and  27.  One  part  of  cement  and  three  parts 
of  sand,  by  volume,  shall  be  thoroughly  mixed  dry,  and  then  made 
into  mortar  with  a  sufficient  quantity  of  water  to  produce  a  mortar 
of  such  consistency  that  it  will  just  flow  freely  into  the  joints 
between  the  stones.  All  the  joints  between  the  stones  must  be 
completely  filled  with  this  mortar  before  it  has  begun  to  set.  The 
mortar  filling  shall  be  brought  even  with,  but  not  above,  the  tops 
of  the  stones.  After  the  filling  is  thus  completed,  the  foundation 
must  stand  undisturbed  until  the  mortar  shall  have  set  firmly,  in 
no  case  less  than  five  days.  The  mortar  must  kept  moist  during  the 
period  allowed  for  setting.* 

Old  stone  foundation  will  be  measured  in  square  yards,  in  place 

after  completion,  the  average  depth  being  taken  as 

inches.  The  contract  price  includes  the  cost  of  handling  and  clean- 
ing the  stone,  supplying  and  placing  the  bed  of  sand,  setting  and 
ramming  the  stone,  supplying  the  materials  for,  making  and  placing 
the  mortar  in  the  joints  and  watering  the  street  while  the  mortar 
is  setting.  Where  stone  is  procured  from  other  streets,  or  from 
storage  yards,  the  Contractor  will  be  required  to  load,  haul  and 

unload  them,  and  will  be  allowed  for  this  service  a  price  of 

cents  per  cubic  yard  for  loading  and  unloading,  plus 


*See  foot-note,  p.  15.  The  cost  of  filling  the  joints  of  old  block  pave- 
ment with  mortar  or  grout  is  considerable.  It  will  hardly  ever  be  less 
than  20  cents  and  may  exceed  35  cents  per  square  yard,  depending-  on  the 
volume  of  joints  and  the  local  cost  of  material  and  labor.  The  cost  of  re- 
setting and  ramming  theblocks  with  proper  care  will  usually  be  from  10 
cents  to  12  cents  per  square  yard,  so  that  the  cost  of  the  foundation, 
exclusive  of  the  value  of  the  blocks,  may  vary  from  30  cents  to  47 
cents  per  square  yard. 

As  a  good  concrete  foundation  6  inches  in  depth  can  be  laid  for 
from  70  to  90  cents  per  square  yard,  it  is  obvious  that  if  the  old 
blocks  can  be  sold  for  as  much  as  the  difference  between  the  cost 
of  the  old  block  and  the  concrete  foundation,  nothing  will  be  saved  by 
using  the  old  block  foundation.  In  at  least  one  city,  asphalt  pavelnent 
is  extensively  laid  over  old  stone  block  foundation  relaid  in  a  very 
careless  manner,  the  joints  being  filled  usually  with  the  old  sand  or 
loam  found  in  the  street,  This  practice  cannot  be  too  strongly  con- 
demned. Asphalt  pavement  surfaces  resting  on  such  a  foundation  are 
necessarily  short-lived  and  unsatisfactory.  The  practice  of  opening  the 
street  to  travel  for  a  period  after  the  blocks  are  relaid  and  before  the 
asphalt  surface  is  applied,  helps,  under  favorable  conditions,  to  con- 
solidate the  foundation,  but  does  not  remove  the  objections  to  it.  If 
heavy  rains  intervene,  the  sub-foundation  becomes  saturated  with 
water,  and  its  resistance  so  reduced  that  the  stone  blocks  settle  out 
of  shape,  particularly  in  soft  spots,  and  they  are  usually  hastily  raised 
and  reset  just  before  the  asphalt  surface  is  applied.  The  result  is 
an  insecure  foundation  fatal  to  the  durability  and  usefulness  of  the 
pavement. 


22 

cents  per  cubic  yard  for  each  one-half  mile,  or  fraction  thereof,  over 
which  they  are  hauled  by  the  nearest  practicable  route,  the  measure- 
ment to  be  made  after  the  stone  is  set  in  the  street,  without  deduc- 
tion for  joints. 

Broken-Stone  Foundation. 

37.  The  sub-grade  for  broken-stone  foundation  shall  be  pre- 
pared  as   specified   in   Section    23,   except   that   the   rolling   may   be 
omitted  at  the  option  of  the  Contractor.      The  broken   or  crushed 
stone  shall  be  of  hard,  durable  stone.     The  foundation  shall  be  con- 
structed in  two  courses,  as  follows: 

The  broken  stone  used  in  the  first  course  shall  be  of  such  size 
that  it  will  all  pass  through  a  screen  having  openings  two  and  one- 
half  (2%)  inches  in  diameter,  and  will  all  be  retained  on  a  screen 
having  openings  one  (1)  inch  in  diameter.  This  stone  shall  be 
evenly  spread  over  the  sub-grade  to  such  a  thickness  that  after 
being  thoroughly  consolidated  by  rolling,  its  upper  surface  shall  be 
three-fourths  inch  below,  and  parallel  to  the  surface  of  the  founda- 
tion when  completed.  It  shall  then  be  rolled  with  a  road-roller  weigh- 
ing not  less  than  ten  (10)  tons  until  the  stone  is  thoroughly  com- 
pacted. 

The  second  course,  composed  of  screenings,  all  of  winch  shall 
have  passed  through  a  screen  with  openings  one  inch  in  diameter, 
shall  then  be  spread  over  the  first  course  and  well  raked  into  the 
voids  of  the  first  course.  It  shall  then  be  thoroughly  wetted,  and 
shall  be  rolled  with  the  ten-ton  roller  until  the  fine  stone  is  driven 
into  the  interstices  of  the  first  course  and  the  whole  thoroughly 
consolidated,  the  wetting  being  repeated  while  the  rolling  continues. 
Additional  screenings  shall  be  added  and  rolled  in  where  necessary 
to  bring  the  surface  to  the  proper  elevation.  When  completed,  the 

top  surface  of  the  foundation  shall  be inches  below, 

and  parallel  to  the  pavement  datum.  No  part  of  the  upper  surface 
of  the  completed  foundation  shall  project  more  than  one-fourth  (  ^  ) 
inch  above,  nor  shall  it  be  more  than  one-half  ( %  )  inch  below  the 
grade  and  contour  above  specified. 

Gravel  of  a  quality  satisfactory  to  the  Engineer  may  be  substi- 
tuted for  broken  stone,  with  his  written  consent.  If  of  assorted 
sizes,  such  as  will  compress  into  a  mass  having  not  more  than  thirty 
(30)  per  cent,  of  voids,  the  foundation  may  be  constructed  in  a 
single  layer,  graded,  watered  and  rolled,  as  prescribed  above  for 
broken  stone.* 

Measurement. 

38.  Broken-stone  and  gravel  foundation  will  be  measured  and 
computed  by  the  cubic  yard  in  the  street  as  completed,  without  any 
allowance  for  consolidation  by  the  roller  or  for  settlement  into  the 


*Where  there  is  a  possibility  that  gravel  may  be  used,  the  con- 
tractor should  be  asked  to  name  prices  for  the  gravel  foundation  as 
well  as  the  stone  foundation,  since,  unless  this  be  done,  the  change  from 
the  one  material  to  the  other  might  be  held  to  be  illeg'al. 


23 

sub-grade,   the   thickness    being   taken    as inches. 

The  contract  price  for  it  shall  cover  the  cost  of  supplying  the  mater- 
ial, placing  it  on  the  street,  and  grading,  watering  and  rolling  it. 

BITUMINOUS  PAVEMENTS. 

Classification. 

39.  Pavements,  the  wearing  surfaces  of  which  are  composed 
of  a  mineral  aggregate  cemented  together  with  bitumen,  shall  be 
classified  as  follows: 

(a).  Asphalt  Pavement:  Composed  of  an  asphaltic  cement 
made  from  natural  asphaltum,  refined  and  tempered,  mixed  arti- 
ficially with  sand  and  finely  pulverized  stone,  or  other  inorganic 
substance. 

(b).  Rock  Asphalt  Pavement:  Composed  of  asphaltum  com- 
bined in  a  natural  state  with  carbonate  of  lime  or  silica  in  such 
ratios  as  to  require  the  addition  of  little  or  no  other  material. 

(c).  Block  Asphalt  Pavement:  .Constructed  of  compressed 
paving  blocks  composed  of  asphaltic  cement,  crushed  stone  and 
other  mineral  aggregate. 

(d).  Bituminous  Concrete:  Composed  of  asphaltum,  or  other 
bitumens  artifically  mixed  with  crushed  stone,  gravel,  sand,  pulver- 
ized carbonate  of  lime,  or  other  material. 


24 


ASPHALT  PAVEMENT.* 

General. 

40.  Asphalt  pavement  surface  shall  be  laid  upon  a  foundation 
of  hydraulic  cement  concrete,  or  of  stone  blocks  relaid,  over  a  sub- 
grade,  to  be  constructed  in  accordance  with  Articles  23,  25,  26, 
27,  28,  29,  30,  31,  32,  33,  34,  35  and  36. 

Asphalt  pavement  surface  shall  be  constructed  in  two  courses, 
called  the  base-course  and  the  surface-course.  The  base-course  may 
be  from  one  (1)  inch  to  one  and  one-half  (l1/^)  inches  thick,  and 
the  surface-course  may  be  from  one  (1)  inch  to  two  (2)  inches 
thick,  as  shall  be  hereafter  specified. 


*The  various  kinds  of  asphalt  now  used  for  street  pavements  differ 
considerably  in  their  physical  and  chemical  properties.  This  makes  it 
necessary,  in  preparing  general  specifications  intended  to  cover  the 
use  of  any  or  all  the  different  kinds  now  recognized  as  acceptable,  to 
provide  greater  latitude  than  would  be  proper  or  desirable  if  the  spec- 
ifications were  intended  to  apply  to  any  one  variety  only.  To  that  ex- 
tent these  specifications  are  defective  and  open  to  criticism.  So  long 
as  it  continues  to  be  the  policy  of  cities  to  admit  general  and  free 
competition  in  the  use  of  the  several  varieties  of  asphalt  under  the 
same  general  specification,  this  defect  cannot  be  avoided. 

The  only  remedy  for  this  state  of  affairs  that  seems*  practicable 
would  be  for  each  cij;y  to  purchase  its  supply  of  asphalt,  after  asking 
proposals  under  suitable  general  specifications,  and  selecting  the  kind 
of  asphalt  which  may  seem  best  and  cheapest  under  the  proposals  sub- 
mitted. The  contractors  for  constructing  the  pavements  would  then 
be  supplied  with  asphalt  by  the  city  at  a  stipulated  price.  The  paving 
specifications  could  then  be  prepared  with  reference  to  the  special 
qualities  of  the  asphalt  to  be  used. 

This  plan  would  possess  a  number  of  other  obvious  advantages. 
A  similar  plan  is  in  use  in  a  number  of  cities  and  by  a  number  of  cor- 
porations in  supplying  hydraulic  cement  to  contractors  for  the  construc- 
tion of  various  works. 

Notwithstanding  the  undesirable  latitude  permitted  in  the  spec- 
ifications here  submitted  for  asphalt  pavement,  it  is  believed  that  they 
are  a  decided  improvement  upon  any  now  in  use,  and  that,  if  properly 
applied  and  enforced,  they  will  enable  the  city  engineer  to  intelligently 
control  and  direct  paving  contracts,  and  to  secure  satisfactory  and  uni- 
form results.  The  typical  specification  for  asp_halt  pavement  hereto- 
fore and  up  to  the  present  time  in  common  use  is  antiquated,  indefinite 
and  unsatisfactory.  It  is  largely  a  survival  of  the  time  when  little 
was  known  of  either  the  technical  or  the  practical  side  of  the  art  of 
constructing  asphalt  pavements,  outside  of  the  promoters  and  contrac- 
tors engaged  in  the  business,  who  consequently  dictated  largely  the 
specifications  for  the  work.  Great  advancements  and  improvements  have 
been  made  in  the  technology  and  the  practical  construction  of  this 
class  of  pavements  in  the  last  decade,  but  not  much  change  has  been 
made  in  the  usual  city  specifications  for  the  work,  and  some  of  these 
specifications  contain  antiquated  requirements  which,  if  literally  en- 
forced, would  prevent  the  attainment  of  the  best  results.  Engineers 
have  relied  largely  upon  the  presumption  that  the  guarantee  clauses  in 
paving  contracts  would  compel  the  contractors  to  do  the  work  in  the 
best  manner,,  and  have  allowed  them  wide  latitude,  in  the  conduct  of 
the  work. 

In  the  present  state  of  the  art  there  is  no  longer  any  good  reason 
why  the  character  of  the  materials  to  be  used,  the  methods  to  be  fol- 
lowed and  the  quality -of  the  work  done  should  not  be  definitely  speci- 
fied, as  is  the  practice  with  other  kinds  of  pavement,  and  with  the  same 
satisfactory  results. 


25 

Crude  Asphalt. 

41.  The  cementing  element  in  asphalt  pavement  shall  be  pre- 
pared from  a  natural  asphalt,  possessing  the  requisite  qualities,  as 
hereinafter  specified.     The  crude  asphalt,  as  obtained  from  the  mines 
or  natural  deposits  shall,  if  necessary,  be  properly  refined  to  drive 
off  water  and  to  separate  extraneous  substances,   by  melting  at  a 
temperature  not  exceeding  four  hundred  and  fifty  (450)  degrees  F. 
Crude   asphalt   of   the   class   commonly   called    "Glance   Pitch"   and 
"Iron  Pitch,"  which  does  not  distinctly  soften  at  a  temperature  of 
one   hundred   and   eightyrfive    (185)    degrees   F.,   and   detached   or 
deteriorated  material  from  otherwise  acceptable  deposits  of  asphalt, 
will  not  be  accepted. 

Refined  Asphalt. 

42.  Refined  asphalt,  other  than  that  prepared  from  the  dis- 
tillation of  asphaltic  oils,  shall  be  free  from  water  and  shall  not 
contain  an  injurious  quantity  of  light  oils,  or  extraneous  matter, 
and  shall  be  homogeneous  throughout  the  mass.     It  shall  contain 
not  more  than  four   (4)  per  cent,  of  organic  matter,  and  not  more 
than  thirty-five    (35)    per  cent,   of  mineral  inorganic  matter  other 
than  bitumen;  and  not  less  than  fifty-six  (56)  per  cent,  of  bitumen 
soluble  in  carbon   di-sulphide.      The   bitumen   extracted   by   carbon 
di-sulphide,   when   freed   from   the  solvent,   shall   not  be   distinctly 
brittle  at  a  temperature  of  eighty   (80)   degrees  F.     Not.  less  than 
sixty  (60)  per  cent,  of  it  shall  be  soluble  in  Pennsylvania  petroleum 
naphtha  of  specific  gravity  seventy-six  (76)  degrees  Baume  at  a  tem- 
perature of  sixty-five  (65)  degrees  F.,  and  at  least  ninety-seven  (97) 
per  cent,   of  it  shall   be  soluble  in   chemically   pure   carbon   tetra- 
chloride.     When  exposed  for  seven   (7)   hours  to  a  temperature  of 
three  hundred  and  twenty-five  (325)  degrees  F.,  in  a  shallow  dish, 
the  bottom  of  which  is  covered  with  the  bitumen  to  a  depth  of  one- 
half  ( MJ  )  inch,  the  refined  asphalt  shall  lose  not  more  than  five  (5) 
per  cent,  by  evaporation. 

Asphalts  that  are  injuriously  affected,  in  the  pavement,  by  water 
(to  be  determined  by  the  test  immediately  hereinafter  described), 
shall  not  be  used  except  under  the  conditions  specified  in  Section  43. 
Cylinders  made  from  the  surface  mixture  it  is  proposed  to  use,  one 
(1)  inch  in  diameter  and  two  (2)  inches  long,  compressed  to  a 
density  of  two  and  one-tenth  (2.1),  when  immersed  forty-five 
(45)  days  in  ten  (10)  times  their  volume  of  rain-water,  shall  retain 
a  sound  surface,  unchanged  and  uncorroded  by  the  action  of  the 
water. 

Asphalts  resulting  from  the  distillation  of  crude  asphaltic  oils 
will  not  be  accepted  unless  the  distillation  shall  have  been  effected 
by  the  use  of  suitable  apparatus,  at  a  temperature  not  exceeding 
seven  hundred  (700)  degrees  F.  The  bitumen  must  not  be  over- 
distilled  and  "cut  back"  by  adding  oil.  The  product,  to  be  acceptable, 
shall  possess  the  following  qualities:  It  shall  melt  and  flow  at  a  tem- 
perature not  below  one  hundred  and  forty  (140)  degrees  F.,  but 


I    UNIVERSITY 


26 

below  a  temperature  of  one  hundred  and  eighty  (180)  degrees  F., 
and  when  tested  in  the  standard  New  York  State  closed  oil-testing 
apparatus  shall  not  flash  at  a  temperature  below  four  hundred  and 
fifty  (450)  degrees  F.  When  exposed  in  a  shallow  dish,  the  bottom 
of  which  is  covered  to  a  depth  of  one-half  (  V2  )  inch  with  the  bitu- 
men, to  a  temperature  of  four  hundred  (400)  degrees  P.,  for  seven 
(7)  hours,  it  shall  not  lose  by  evaporation  more  than  seven  (7)  per 
cent,  by  weight.  Not  less  than  ninety-eight  (98)  per  cent,  shall  be 
soluble  in  cold  carbon  di-sulphide,  and  not  less  than  sixty-five  (65) 
per  cent.,  nor  more  than  seventy-five  (75)  per  cent,  of  the  bitumen 
shall  be  soluble  in  cold  Pennsylvania  naphtha  of  gravity  eighty-eight 
(88)  degrees  Baume.  Not  less  than  ninety-seven  (97)  per  cent,  of 
the  bitumen  shall  be  soluble  in  carbon  tetra-chloride,  and  it  shall 
not  contain  more  than  sixteen  (16)  per  cent,  of  fixed  carbon.* 

Bitumens  resulting  from  destructive  distillation  or  from  arti- 
ficial oxidation,  and  bituminous  compounds  prepared  from  oil  or  oil 
residuums  heated  with  sulphur  or  other  substances,  will  not  be 
accepted,  nor  shall  they  be  mixed  with  the  asphalt  used.t 

43.  Asphalts  that  are  injuriously  affected  by  water,  and  those 
whose  practical  value  for  making  pavements  has   not   been  estab- 
lished, in  the  judgment  of  the  City,  by  sufficient  experience,  will  not 
be  accepted  except  under  such  special  bond  and  guaranty  provisions 
as  the  City  may  prescribe.  $ 

44.  Full  information  as  to  the  source  and  character  of  the 
crude  asphalt  and  the  method  of  refining  it  shall  be  furnished  to  the 
Engineer  and  verified  by  such  evidence  as  he  may  require. 


*There  has  been  much  discussion  as  to  the  suitableness  of  these 
oil  asphalts,  called  "residual  pitches,"  for  use  in  making  asphalt  pave- 
ments. When  properly  prepared  from  suitable  asphaltic  oils,  so  as  to 
comply  with  the  specifications  here  given,  there  can  be  no  doubt  that 
good  pavements  can  be  made  with  them.  But  as  they  appear  on  the 
market,  being  usually  produced  at  different  localities  and  refineries 
from  crude  oils  of  differing  qualities,  distilled  by  somewhat  differing 
methods,  and  usually  at  temperatures  of  from  900  degrees  to  1200 
degrees,  they  are  likely  to  vary  so  greatly  in  quality  as  to  make  their 
use  inadvisable  without  careful  technical  inspection.  Unless,  therefore, 
the  engineer  is  prepared  to  make,  or  to  have  such  inspection  made,  it 
is  hardly  wise  or  safe  to  permit  their  use.  They  stand,  in  this  respect, 
upon  a  footing  different  from  the  better-known  natural  asphalts  ob- 
tained from  large  deposits  of  practically  uniform  character  and  quality, 
where  the  simpler  process  of  refining  is  less  likely  to  effect  injuriously 
the  chemical  quality  of  the  material. 

It  may  be  confidently  predicted  that  any  of  these  "residual 
pitches"  which  comply  with  these  specifications  will,  if  properly 
handled,  make  a  good  pavement. 

tThe  possibility  that  some  of  these  compounds,  or  artificial  as- 
phalts, may  be  suitable  for  use  in  pavements  is  not  denied.  But  in 
the  absence  of  a  fuller  knowledge  of  them  than  we  now  have,  and  in 
the  light  of  present  experience,  the  only  safe  course  is  to  reject  them. 

Jit  is  not  intended  here  to  enter  into  an  extended  discussion  of 
the  fact  that  some  asphalts  are  injuriously  affected  by  water,  and  the 
bearing  which  this  fact  should  have  upon  the  selection  of  an  asphalt 
for  pavement  purposes.  There  can  be  no  doubt  that  modern  treatment 
and  methods  of  construction  have  tended  to  diminish  but  not  wholly 
to  prevent  the  disintegrating  effect  of  water  upon  pavements  made  with 
such  asphalt,  and  if  the  engineer  could  be  certain  that  his  pavements 
would  be  constructed  by  contractors  guided  by  long  experience  and  the 
best  expert  advice,  he  might  perhaps  safely  disregard  this  provision. 
Since  in  practice  he  can  have  no  such  assurance,  the  provision  is  a  wise 
one  and  it  does  not  involve  any  serious  or  material  hardship  to  the  con- 
tractor. 


27 

Softening  OP  Tempering  Agent. 

45.  For  softening  and   tempering  refined  asphalt,   petroleum 
residuum  oil  shall  be  used.     It  shall  be  free  from  water,  coke  and 
other  impurities.     Its  specific  gravity  shall  not  be  below  0.925,  nor 
above  0.958.     Its  flash  test  (determined  in  the  standard  New  York 
State  closed  oil-testing  apparatus)  shall  not  be  under  three  hundred 
and  fifty  (350)  degrees  F.,  and  when  exposed  for  seven  (7)  hours 
to  a  temperature  of  three  hundred  and  twenty-five   (325)   degrees 
F.,  in  a  shallow  open  dish,  the  bottom  of  which  is  covered  by  the 
oil  to  a  depth  of  one-half   (%)   inch,  it  shall  not  lose  more  than 
seven  (7)  per  cent,  by  evaporation.     It  shall  not  contain  more  than 
ten  (10)  per  cent,  of  paraffine  scale. 

Sand. 

46.  A  superior  quality  of  sand  will  be  required  and  this  must 
be  secured,  if  necessary,  by  the  admixture  of  two  or  more  sands. 
The  sand  shall  be  silicious  and  so  free  from  organic  matter,  mica, 
soft  grains,   and   other  impurities,   that  these   shall   not  aggregate 
more  than  two   (2)   per  cent,  of  the  mass.     The  grains  shall,  pre- 
ferably, be  moderately  "sharp"  or  angular,  and  must  be  of  assorted 
sizes  so  that  the  voids  in  the  compacted  mass  of  dry  sand  shall  not 
exceed  thirty-three   (33)   per  cent.     A  typical  sand,  to  be  approxi- 
mated as  closely  as  practicable,  would  give  the  following  sieve  tests, 
the  sieves  being  used  in  the  order  named: 

3%   of  the  whole  will  pass  No.  200  sieve. 
15%     "     "        ,"          "        "      "     100      " 
18%     "     "          "          "        "      "        80       " 
30%     "     "    ,      "          "        "      "        50 

10%   "    ••  "     "    "     10    •• 

and  none  will  fail  to  pass  the  No.  10  sieve.* 

Pulverized  Stone. 

47.  This  may  consist  of  limestone  or  other  sound  stone  or 
sand,  pulverized  to  such  fineness  that  the  whole  will  pass  the  No.  50 
sieve,  not  more  than  ten  (10)  per  cent,  will  be  retained  on  the  No. 
100  sieve,  and  at  least  seventy  (70)  per  cent,  of  it  will  pass  the  No. 
200  sieve.     Portland  cement  may  be  partly  substituted  for  pulver- 
ized stone,  where  the  Engineer  shall  so  direct.t     Portland  cement 
thus  used  will  be  paid  for  at  the  price  bid  per  barrel  for  the  same, 
in  addition  to  the  price  paid  per  square  yard  for  the  pavement  sur- 
face. 


*It  is  now  well  recognized  that  the  character  and  quality  of  the 
sand  used  is  one  of  the  most  important  elements  in  determining  the 
utility  and  durability  of  an  asphalt  pavement.  A  satisfactory  sand 
should  be  insisted  on,  even  if  it  involves  a  very  considerable  increase 
in  the  first  cost  of  the  work. 

While  our  knowledge  of  the  subject  is  not  complete,  experience 
seems  to  indicate  pretty  clearly  that  a  sand  of  the  quality  and  size- 
grading  here  specified  as  typical,  may  be  depended  upon  to  produce  a 
good  pavement. 

tThe  use  of  Portland  cement  in  surface  mixtures  to  be  laid  on 
streets  of  heavy  travel,  or  those  exposed  to  damp  foundations,  is  very 
strongly  recommended.  On  streets  of  the  heaviest  travel,  -or  where  the 


28 

Stone  for  Base-Course. 

48.  Stone  screenings  for  base-course  shall  be  of  crushed,  hard, 
durable  stone.     The  portion  used  shall  all  be  retained  upon  a  No.  8 
sieve,  or  screen,  and  shall  all  pass  a  screen  having  square  meshes 
the  linear  dimensions  of  which  are  one-fourth    (  %  )   inch  less  than 
the  thickness  of  the  base-course. 

Asphaltic  Paving  Cement. 

49.  The  asphaltic  paving  cement  shall  be  prepared  from  the 
crude  and  refined  asphalt  specified  in  Sections  41  and  42,  tempered 
and  softened,  if  necessary,  by  the  addition  of  petroleum  residuum 
to  the  consistency  and  hardness  specified  below. 

The  refined  asphalt  and  the  petroleum  residuum  oil  shall  be 
mixed  and  melted  together  at  a  temperature  not  below  two  hundred 
and  seventy-five  (275)  degrees  F.,  and  thoroughly  incorporated  by 
agitation  or  stirring  until  a  homogeneous  cement  be  produced.  The 
mass  shall  not  be  heated  to  a  temperature  exceeding  three  hundred 
and  twenty-five  (325)  degrees  F.,  and  the  stirring  or  agitation  shall 
be  continued  until  the  cement  be  used. 

The  asphaltic  cement,  when  tested  at  a  temperature  of  seventy- 
eight  (78)  degrees  F.,  in  a  standard  Dow  penetration  apparatus, 
shall  give  a  penetration  of  from  forty  (40)  to  eighty  (80)  degrees, 
as  the  Engineer  may  determine.  When  a  cement  of  the  proper  con- 
sistency and  hardness  shall  be  determined  upon  and  approved  by  the 
Engineer,  samples  of  it  shall  be  kept  as  a  standard  and  all  subse- 
quent batches  must  be  made  to  conform  thereto,  suitable  apparatus 
and  tests  being  employed  to  determine  the  correspondence  of  each 
kettle  of  cement  with  the  standard.  The  asphaltic  cement,  when  at 
or  slightly  below  its  melting  temperature,  shall  be  so  viscous  that  it 
will  draw  out  into  long,  fine  threads  which  shall  be  free  from  lumps 
or  raggedness,  and  it  shall  possess  satisfactory  cementitious  quali- 
ties. 
Composition  and  Preparation  of  Asphalt  Surface  Mixture. 

50.  The  surface   course   shall   be   composed   of   the   materials 
specified  in  Sections  41,  42,  43,  44,  45,  46,  47  and  49,  mixed  in  such 
ratios  by  weight  as  the  Engineer  may  direct  or  approve.     A  typical 
mixture  will  contain: 

Sand 100.0    Ibs. 

Pulverized  mineral  matter  passing  No.  200  screen, 

including  that  found  in  the  paving  cement.  .    17.5      " 

v      Pure  bitumen  (in  paving  cement) 13.5 

But  the  quantities  of  pulverized  stone  and  of  asphaltic  cement  shall 
be  varied  as  may  be  found  necessary  or  desirable  by.  the  Engineer 
to  suit  the  purity  of  the  asphaltic  cement,  the  character  of  the  sand. 


pavement  will  be  exposed  to  unfavorable  conditions  of  dampness,  par- 
ticularly if  the  pulverized  stone  is  not  very  finely  ground,  the  Port- 
land cement  may  constitute  ten  per  cent,  of  the  pulven-'ed  material,  or 
"dust,"  as  it  is  commonly  called.  Ordinarily  from  five  to  seven  per 
cent,  may  be  used  to  advantage  on  all  streets  of  comparatively  heavy 
travel. 


29 

the  climatic  conditions,  and  the  varying  quantity  and  character  of 
travel  on  the  street  to  be  paved;  and  Portland  cement  may  be  sub- 
stituted partly  or  wholly  for  the  pulverized  stone,  when  directed 
by  the  Engineer.  The  surface-course  mixture  shall  be  submitted 
to  the  Engineer  and  approved  by  him  before  any  is  laid  upon  the 
street. 

The  mixing  shall  be  accomplished  in  a  mechanical  mixing 
apparatus  capable  of  rapidly  and  effectually  incorporating  the  mater- 
ials together,  and  each  batch  must  remain  in  the  mixer  a  sufficient 
length  of  time  to  effect  a  perfect  mixture.  The  sand  shall  be 
separately  heated  and  shall  reach  the  mixing  apparatus  at  a  tem- 
perature not  above  three  hundred  and  twenty-five  (325)  degrees  F. 
The  pulverized  stone  shall  be  at  such  a  temperature  that  when 
mixed  with  the  sand  the  temperature  of  the  mixed  mass  shall  not 
be  above  three  hundred  and  twenty-five  (325)  degrees  F.,  nor  below 
three  hundred  and  ten  (310)  degrees  F.  The  sand  shall  be  first 
placed  in  the  mixer,  followed  by  the  pulverized  stone,  and  these  two 
materials  shall  be  thoroughly  mixed  together  before  the  asphaltic 
cement  is  added.  The  asphaltic  cement  at  a  temperature  not  above 
three  hundred  and  twenty-five  (325)  degrees,  nor  below  three 
hundred  (300)  F.  shall  then  be  added  in  such  a  way  as  to  evenly 
distribute  it  over  the  sand  and  pulverized  stone,  and  the  mixing 
continued  until  the  materials  are  thoroughly  incorporated  into  a 
perfectly  uniform  and  homogeneous  mass,  with  the  grains  of  sand 
completely  covered  with  cement.  Suitable  thermometers  shall  be 
constantly  used  to  determine  the  temperatures  specified  herein. 
Great  care  must  be  taken  to  accurately  weigh  and  proportion  the 
materials  charged  into  the  mixer.* 

Composition  of  Base-Course. 

51.  The  base-course  shall  be  composed  of  the  crushed  stone 
specified  in  Section  48,  mixed  with  the  asphaltic  cement,  sand  and 
pulverized  stone  specified  in  Sections  49,  46  and  47,  but  the  asphaltic 
cement  shall  give  a  penetration  with  the  Dow  apparatus  of  from 
seventy  (70)  to  eighty  (80)  degrees,  as  the  Engineer  may  direct. 
A  typical  base-course  mixture  will  be  composed  as  follows: 

Crushed    stone. 100       lt>s. 

Sand   42 

Pure  bitumen  (in  asphaltic  cement) 7        " 

Pulverized  stone 7  %    " 

But  the  mixture  shall  be  such  that  when  placed  on  the  street  and 
compressed  by  the  roller  the  mass  shall  be  dense  and  the  voids  in 


*It  should  be  noted,  in  a  general  "way,  that  there  is  quite  a  difference 
In  the  temperature  to  which  different  asphalts  may  be  safely  subjected. 
Trinidad  asphalt  will  not  be  injured  by  the  higher  range  of  tem- 
peratures named  in  these  specifications,  while  Bermudez  and  some  other 
asphalts  should  be  worked  at  as  nearly  as  possible  to  the  lower  range 
of  temperatures  named.  The  relative  amount  of  loss  of  the  different 
asphalts  when  exposed  for  seven  hours  to  the  temperature  of  325  de- 
grees (sect.  42)  will  supply  a  rough  practical  guide  as  to  the  tempera- 
ture permissible — the  greater  the  loss,  the  closer  should  the  lower 
range  of  temperatures  be  adhered  to. 


30 

the  stone  completely  filled;  and  to  accomplish  this  the  quantity  of 
crushed  stone  used  in  the  mixture  may  be  increased  or  decreased, 
as  the  volume  of  its  voids  may  require,  in  order  that  they  may  be 
completely  filled.* 

Mixing  the  Base-Course. 

52.  The  materials  for  the  base-course  shall  be  mixed  in  the 
same  general  manner  as  prescribed  for  the  surface  course  (Sect.  50), 
the  crushed  stone  being  delivered  first  in  the  mixer.     The  temper- 
ature of  the  materials  being  not  above  three  hundred  and  twenty- 
five  (325)  degrees  F.,  nor  below  three  hundred  (300)  degrees  F. 

Laying  Asphalt  Pavement. 

53.  Asphalt  pavement  must  not  be  laid  except  when  the  surface 
upon  which  it  is  to  be  placed  is  dry;   nor  when  the  temperature  of 
the  air  is  below  thirty-two    (32)    degrees  F.,   or  if  a  strong  wind 
prevails,    when    the    temperature    of    the    air    is    below    forty    (40) 
degrees  F. 

The  pavement  mixture,  whether  for  base-  or  surface-course, 
shall  be  taken  to  the  street  as  soon  after  it  leaves  the  mixer  as 
practicable.  When  the  temperature  of  the  air  is  below  eighty  (80) 
degrees  F.,  the  loaded  vehicles  conveying  the  mixture  to  the  street 
shall  be  covered  by  canvas  covers  to  prevent  the  escape  of  heat. 
When  unloaded  upon  the  street,  the  temperature  of  the  mass  should 
not  be  below  two  hundred  and  sixty  (260)  degrees  F.,  and  any  load 
or  portions  of  a  load  found  under  two  hundred  and  forty  (240) 
degrees  F.  must  be  rejected.  After  being  unloaded  on  the  street, 
the  mixture  must  be  shovelled  into  place  in  such  a  manner  that  the 
whole  of  it  will  be  moved  from  the  pile  into  which  it  was  unloaded. 

Laying  the  Base-Course. 

54.  The  base-course  will   have  an   average   thickness   of   one 
and  one-quarter    ( 1  *4 )    inches  after  compression.     It  shall  be  laid 
directly  upon  the  pavement  foundation,  which  must  be  free  from  all 
loose  fragments  and  rubbish  and  be  swept  clean  in  advance  of  the 
application  of  the  base-course.      The  base-course  mixture  shall  be 
spread  upon  the  foundation  and  evenly  and  regularly  graded  to  such 
a   depth   that  after   compression   by  the  roller   its  surface   will   be 

inches  below,  and  truly  parallel  to,  the  pavement 

datum. 

Great  care  must  be  taken  in  handling,  spreading  and  grading 
the  mixture  to  maintain  the  uniform  admixture  of  the  crushed 
stone  throughout  the  mass.  The  rakes  used  must  have  tines  wide 
apart,  and  the  back  of  the  rake  must  be  principally  used  for  grading. 
Immediately  after  being  graded,  and  while  still  hot,  the  base-course 


"The  open  base  course,  or  "binder,"  composed  only  of  crushed  stone, 
coated  with  pitch  or  asphaltic  cement,  extensively  and  almost  exclusive- 
ly used  up  to  a  recent  date,  is  no  longer  advocated  by  the  best  author- 
ities on  asphalt  pavements.  The  aim  is  now  to  make  the  base  course 
as  dense  and  strong  as  the  surface  course. 


31 

shall  be  rolled  with  a  ten-ton  asphalt  roller,  the  rolling  being  con- 
tinued until  no  further  compression  takes  place. 

The  base-course  must  not  be  laid  more  than  one  day's  work  in 
advance  of  the  surface. 

When  the  base-course  is  completed  it  must  present  a  uniform 
appearance  and  texture  over  the  whole  surface,  which  must  conform 
so  truly  to  the  designed  grade  and  contour  that  a  twelve-foot  tem- 
plate, when  applied,  will  show  no  departure  from  the  true  surface 
greater  than  one-quarter  (  ^4  )  inch. 

Laying  the  Surface-Course. 

55.  In  delivering  the  surface-course  mixture  upon  the  base- 
course,  care  must  be  taken  not  to  break  or  disturb  the  latter.  Any 
breaks  made  in  the  base-course  must  be  so  repaired,  before  the  sur- 
face course  is  spread,  as  to  be  equal  in  density  and  surface  to  the 
adjoining  base. 

Before  the  surface-course  is  spread  the  base-course  must  be 
thoroughly  cleaned  and  all  rubbish,  loose  material  and  street  dirt 
removed. 

The  material  for  the  surface-course  shall  be  so  evenly  spread 
and  graded  with  asphalt  rakes  that  after  it  is  properly  compacted 
by  rolling,  the  surface  will  coincide  with  the  pavement  datum 
within  the  limits  named  below.  In  grading  the  material,  all  lumps 
must  be  broken  up  and  the  whole  reduced  to  a  finely  comminuted 
mass  of  equal  density  throughout.  Directly  after  being  so  graded 
it  shall  be  rolled  with  a  hand-roller,  or  light  steam-roller,  to  partly 
compress  the  material,  and,  when  so  directed  by  the  Engineer,  the 
surface  shall  then  be  ironed  with  smoothing  irons  heated  to  a  tem- 
perature that  will  melt,  but  will  not  burn,  the  asphaltic  cement.  A 
thin  layer  of  hydraulic  cement,  just  sufficient  to  prevent  adhesion 
between  the  material  and  the  roller,  shall  then  be  swept  over  the 
surface,  which  shall  at  once  be  thoroughly  rolled  with  a  ten-ton 
asphalt  roller  until  the  material  shall  be  thoroughly  compressed 
and  its  surface  is  brought  to  the  exact  grade  and  contour  designed 
for  the  street  surface.  The  work  of  the  ten-ton  steam-roller  must 
begin  before  the  material  has  cooled  below  two  hundred  (200) 
degrees  F.,  and  be  continued  until  the  roller  makes  no  further 
impression  upon  the  surface.  The  first  course  of  the  heavy  rolling 
shall  be  parallel  to  the  street,  after  which  it  should  be  diagonally 
rolled.,  and  also  cross-rolled  if  the  width  of  the  street  permits.*  Any 
portions  of  the  surface  not  accessible  to  the  roller  shall  be  rammed 
with  hot  rammers  until  compacted  equally  with  the  rolled  portion. 
When  completed,  the  surface  shall  have  an  average  thickness  of 
inches  and  must  be  so  free  from  waves  or  irregu- 


*The  importance  of  proper  and  thorough  rolling  is  not  usually  fully 
appreciated,  and  this  part  of  the  work  is  often  shirked  by  the  contrac- 
tor. Not  only  should  the  heavy  roller  be  at  work  as  soon  as  the  ma- 
terial will  bear  it,  but  the  roller  should,  when  work  is  progressing 
regularly,  be  kept  at  work  all  the  time.  It  is  a  safe  motto  that  th« 
rolling  can  not  be  overdone. 


32 

larities  that  a  template  not  less  than  twelve  feet  long,  when  applied 
to  the  street  surface  shall  nowhere  show  a  divergence  from  the 
designed  true  surface  of  more  than  three-sixteenths  (3-16)  inch, 
and  a  template  sixteen  (16)  feet  long  applied  to  the  gutters  shall 
show  no  divergence  from  the  true  gutter  grade  greater  than  one- 
eighth  (%)  inch. 

Before  the  surface-course  is  placed,  all  exposed  surfaces  of 
curbs,  crosswalks,  manholes,  etc.,  with  which  the  surface-course 
will  be  in  contact,  must  be  well  painted  with  hot  paving  cement  or 
approved  pitch.  The  street  shall  not  be  opened  to  travel  until  the 
pavement  has  become  cold  and  hard. 

Street  Railroad  Tracks. 

56.  Where  railroad  tracks  exist  on  the  streets,  the  sub-grade 
and  the  pavement  foundation  shall  extend  under  the  tracks,  uninter- 
rupted except  by  the  ties  and  other  structures  connected  with  the 
track.      Where   concrete   foundation   is   used,   special   care   must  be 
taken  with  the  concrete  directly  under  or  around  the  rails,  and  con- 
crete made  of  fine  crushed  stone  and  a  higher  ratio  of  cement  and 
sand  may  be  required  in  contact  with  the  rail.     The  concrete  must 
be  thoroughly  tamped  under  and  against  the  rail. 

The  asphalt  surface  shall  be  laid  directly  against  the  rails, 
which,  if  their  temperature  be  under  fifty  (50)  degrees  F.,  shall  be 
heated  by  suitable  appliances  to  a  temperature  of,  or  above,  sixty 
(60;  degrees  F.  immediately  before  the  asphalt  material  is  placed 
around  the  rail.  The  hot  asphalt  material  must  be  thoroughly 
tamped  against  and  along  the  rail  and  under  any  projecting  portions 
of  it,  and  the  surface  of  the  pavement  must  be  even  with,  or 
slightly  (not  more  than  one-eighth  (%)  inch)  above  the  top  of  the 
rail.  Slot-rails  will  be  treated  in  the  same  manner,  subject  to  such 
modifications  as  their  forms  may  necessitate.* 
Plant. 

57.  The  plant  for  making  asphalt  paving  mixtures  must  be  of 
approved    modern    design,    adapted    to    do    the   work    properly,    and 
equipped  with  efficient  machinery.     It  shall  be  of  sufficient  capacity 
to  turn  out  at  least  twelve  hundred  square  yards  of  pavement  surface 
daily  without  crowding.     Weighing  and  measuring  devices  shall  be 
accurate  and  adapted  to  the  purpose,  and  must  be  frequently  tested 
and   adjusted.      Each   plant   must   be   supplied   with   the   apparatus 
necessary  to  make  all  determinations  and  tests  required  at  the  plant 
to  properly  conduct  the  work  in  accordance  with  these  specifications. 
Steam-rollers   must   be   properly   balanced    and   the   rolling   surface 
must  be  true  and  smooth.      All  the  street  tools  used   must  be  of 
approved  kind  and  quality  and  must  be  kept  in  good  working  order. 


*There  is  still  a  wide  difference  of  opinion  as  to  the  advisability 
of  laying  the  asphalt  surface  directly  against  the  rail,  many  engineers 
preferring  to  set  one  or  more  courses  of  paving  brick,  or  stone  pav- 
ing blocks  between  the  rail  and  the  edge  of  the  asphalt.  The  writer's 
experience  is  to  the  effect  that,  if  the  work  is  properly  done,  the  first- 
named  form  of  construction  is  preferable.  If  the  asphalt  be  laid  against 
a  rail  so  cold  that  the  asphalt  material  in  contact  with  or  near  the  rail 


33 

ROCK  ASPHALT  PAVEMENT. 

58.  Rock  asphalt  paving  surface  shall  be  laid  upon  a' concrete 
foundation  prepared  as  specified  in  Articles  23,  25,  26,  27,  28,  29, 
30,  31,  32,  33,  34  and  35. 

Material. 

59.  The  material  for  a  rock  asphalt  paving  surface  shall  be  a 
natural  bituminous  limestone  or  sandstone,  or  a  mixture  of  two  or 
more  such  materials.     Rock  asphalt  shall  be  fine  grained,  of  uniform 
texture  and  hardness,  with  the  bitumen  evenly  distributed  through- 
out the  mass.     It  may  contain  not  less  than  six  and  one-half  ( 6  % ) 
nor  more  than  twelve  (12)  per  cent,  by  weight  of  bitumen,  but  the 
mixture  laid  upon  the  street  shall  not  contain  less  than  nine   (9) 
nor  more  than  ten  (10)   per  cent,  of  bitumen  not  volatile  at  three 
hundred  (300)  degrees  F.,  and,  when  necessary,  richer  or  leaner  rock 
asphalts  must  be  combined  to  secure  this  result.     As  delivered,  it 
shall  be  free  from  earth,  rubbish  and  all  extraneous  matter.     It  shall 
be  subject  to  such  examinations  and  tests  as  the  Engineer  may  deem 
necessary  to  determine  its  character  and   quality.      Rock  asphalt* 
other  than  the  standard  products  of  the  mines  known  as  Val  de 
Travers,  Seyssel,  Vorwohle,  Limmer  and  Ragusa  will  not  be  accepted 
without  the  special  permission  of  the  Engineer,  after  full  investiga- 
tion, and  pavements  laid  from  such  material  shall  be  subject  to  tfc\. 
conditions  of  Section  43,  and  such  other  conditions  and  restrictions 
as  he  may  prescribe. 

Preparation. 

60.  The  natural  rock  shall  be  broken  and  pulverized  so  that 
all  will  pass  through  a  sieve  having  meshes  or.  openings  not  larger 
than  one-tenth  (1-10)   of  an  inch  in  their  longest  side  or  diameter. 
If  the  admixture  of  two  or  more  varieties  be  necessary  to  secure  the 
proper  percentage  and  consistency  of  bitumen,  the  admixture  will  be 
made  after  pulverization  and  before  .heating,  and  in  definite  ratios 
by  weight.     The  powder  shall  be  heated  in  suitable  apparatus  to  a 
temperature  not  exceeding  two  hundred  and  fifty  (250)  degrees  P., 
care  being  taken  that  no  part  of  it  shall  be  burned,  and  it  shall  be 
conveyed  to  the  street  while  hot. 


is  chilled  before  it  can  be  compressed,  the  work  will  necessarily  be 
unsatisfactory.  As  to  durability,  wheels  following  the  line  of  the  rail 
or  of  the  paving  blocks  will  sooner  or  later  form  a  rut  in  the  asphalt 
which  will  require  repair; — and  there  is  not  much  difference  in  the  re- 
sults. The  attempts  to  prevent  the  formation  of  ruts  by  setting  blocks 
alternately  as  headers  and  stretchers  is  not  always  successful,  even 
when  the  work  is  well  done,  and  the  difficulty  of  properly  compressing 
the  tongues  of  asphalt  between  the  headers  is  so  great  that  it  is 
usually  not  well  done.  The  asphalt  settles  under  travel  or  is  gouged 
out,  leaving  a  streak  of  rough  pavement,  and  the  difficulty  and  cost 
of  repairs  is  considerably  increased.  When  paving  blocks  or  bricks 
are  used,  they  should  be  firmly  and  carefully  set  in  the  concrete  foun- 
dation. Probably  the  most  satisfactory  construction  of  this  kind  con- 
sists of  two  or  three  lines  of  the  best  paving  brick  set  with  their 
length  parallel  to  the  rail.  It  is  somewhat  easier  to  get  at  and  repair 
rail  joints  with  this  construction. 


34 

Placing  on  the  Street. 

61.  '  The  mixture  thus  prepared  shall  be  brought  to  the  street 
in  suitable  wagons  or  carts,  and  when  applied  to  the  foundation  its 
temperature  shall  not  be  below  two  hundred    (200)    degrees  F.     It 
shall  be  spread  upon  the  street  foundation  in  a  uniform  layer  of 
such  depth  that  after  being  fully  compressed,  it.  shall  have  a  thick- 
ness of inches.     The  material  shall  then  be  thoroughly 

compressed  by  tamping,  smoothing  or  rolling.     The  whole  operation 
must  be  completed  before  the  material  has  cooled  to  a  temperature 
at  which  it  ceases  to  be  plastic.     The  completed  surface  of  the  pave- 
ment shall  be  sound   and   smooth   and   shall   truly   conform   to   the 
designed  grade  and  contour  of  the  street  surface,  and  the  completed 
surface  shall  comply  with  the  template  tests  named  in  Section  55. 
Travel  upon  the  street  shall  not  be  permitted  until  the  asphalt  sur- 
face becomes  cold  and  hard. 

Street  Railroad  Tracks. 

62.  Where  railroad  tracks  exist  in  the  street  to  be  paved,  the 
work  along  them  shall  be  done  in  the  same  manner  as  prescribed 
for  asphalt  pavement,  Section  56. 


35 

BLOCK  ASPHALT  PAVEMENT. 

Sub-Grade  and  Foundation. 

63.  The  sub-grade  for  asphalt  block  pavement  shall  be  pre- 
pared in  accordance  with  Section  23. 

The  foundation  shall  be  of ,  constructed 

as  specified  in  Sections * 

The  upper  surface  of  the  foundation  shall  be  at  such  grade  as 
will  bring  the  upper  surface  of  the  blocks,  when  laid,  truly  to  the 
pavement  datum. 

Asphalt  Blocks. 

64.  Asphalt  blocks  shall  not  be  less  than  four   (4)   nor  more 
than  six  (6)  inches  wide,  ten  (10)  to  twelve  (12)  inches  long,  and 

inches  in  depth. f     Blocks  for  the  same  street  must 

be  of  the  same  width  and  depth  throughout,  and  no  blocks  varying 
more  than  three-sixteenths    (3-16)    inch  from  the  standard  dimen- 
sions will  be  accepted.      Blocks  that  are  chipped,  cracked,  or  are 
otherwise  imperfect  shall  be  rejected. 

Material  and  Composition. 

65.  Asphalt  paving  blocks  will  be  composed  of  crushed  trap 
rock,    or    equally    hard    and    durable    rock,    pulverized    stone,    and 
asphaltic  cement. 

The  crushed  rock  shall  be  of  such  sizes  that  all  will  pass  a 
screen  having  meshes  one-third  (1-3)  inch  square,  at  least  forty  (40) 
per  cent,  shall  be  held  on  the  number  20  sieve,  and  at  least  ten  (10) 
per  cent,  shall  pass  the  number  100  sieve.  It  must  be  free  from  dirt 
and  other  extraneous  substances. 

The  pulverized  stone  shall  comply  with  Section  47,  and  the 
asphaltum  and  asphaltic  cement  shall  comply  with  Sections  41,  42, 
43,  44,  45,  46,  47  and  49. 

Making  the  Blocks. 

66.  The  crushed  rock,  pulverized  stone  and  asphaltic  cement 
shall  be  heated  and  thoroughly  mixed  in  suitable  proportions,  but 
the  bitumen  shall  not  fall  below  six  and  one-half  (6^)  nor  exceed 
eight  (8)  per  cent,  of  the  whole,     The  quantity  of  pulverized  stone 
shall  not  be  less  than  ten   (10)   per  cent,  and  may  be  increased  to 
compensate  for  the  absence  of  inorganic  matter  other  than  bitumen 
in  the  asphalt  used.     The  asphaltic  cement  must  not  be  heated  to  a 
temperature  that  will  injure  it. 


"The  practice  of  laying  asphalt  block  pavement  upon  crushed  stone, 
or  a  sand  foundation,  on  streets  carrying  a  considerable  travel,  is  in- 
advisable. See  foot-note,  page  15. 

tit  is  a  common  practice  in  a  number  of  cities  where  blocks  4x6x12 
inches  are  used,  to  lay  them  on  their  sides,  making  the  depth  dimension 
four  inches.  This  is  all  right  for  private  driveways  and  for  streets  of 
light  travel:  but  for  streets  having  considerable  or  heavy  travel  such 
blocks  should  always  be  set  on  edge,  making  the  depth  of  the  pavement 
six  inches. 


36 

The  hot  mixture  will  be  compressed  in  molds,  under  a  pressure 
not  less  than  four  thousand  (4000)  pounds  per  square  inch.*  The 
completed  blocks  shall  have  a  specific  gravity  of  not  less  than  two 
and  one-half  (2.5).  When  broken,  the  exposed  surface  shall  appear 
compact  and  uniform  in  composition,  without  voids  or  spongy  por- 
tions. When  subjected  to  1800  revolutions  in  the  standard  rattler 
for  testing  brick  (Section  85),  at  a  temperature  of  seventy  (70) 
degrees  F.,  the  blocks  shall  not  lose  more  than  twelve  (12)  per  cent. 
of  their  weight. 

Laying  the  Blocks. 

67.  The  foundation  shall  be  first  cleaned  of  dirt,  rubbish  or 
loose  material. 

When  the  blocks  are  four  (4)  inches  or  less  in  depth,  they  shall 
be  set  upon  a  bed  of  mortar  made  and  applied  to  the  foundation  in 
the  following  manner: 

The  mortar  shall  be  composed  of  Portland  cement  and  sand, 
complying  with  the  requirements  of  Sections  26  and  27  (a  slow 
setting  cement  being  preferred),  in  the  ratio  of  one  (1)  part  cement 
to  four  (4)  parts  of  sand,  thoroughly  mixed  with  sufficient  water  to 
make  a  rather  soft  mortar.  This  mortar  shall  be  spread  over  the 
foundation,  which  shall  be  previously  wetted,  in  a  layer  approxi- 
mately one-half  (  y2  )  inch  thick  and  its  top  graded  by  the  use  of 
templates  to  a  surface  at  such  depth  below,  and  truly  parallel  to  the 
pavement  datum,  that  when  the  blocks  are  firmly  set  in  it  and 
rammed  their  tops  will  be  in  the  true  grade  and  contour  of  the 
pavement.  The  mortar  shall  be  made  and  spread  only  as  required 
in  the  progress  of  block  laying,  and  any  mortar  that  has  begun  to 
set  before  the  blocks  are  in  place  and  rammed,  shall  be  removed 
and  fresh  mortar  substituted.  The  blocks  shall  be  set  upon  this 
mortar  bed  with  their  longest  dimension  across  the  street,  in  con- 
tinuous courses  which  shall  be  straight  and  at  right  angles  to  the 
axis  of  the  street.  The  block  layers  must  stand  upon  the  blocks 
already  laid  and  not  upon  the  mortar.  The  blocks  and  the  courses 
of  blocks  shall  be  set  as  closely  together  as  practicable.  Blocks  in 
adjoining  courses  must  break  joint  not  less  than  four  inches.  Whole 
blocks  only  will  be  used,  except  as  fillers  at  the  ends  of  the  courses 
or  in  fitting  the  pavement  around  manholes  or  other  structures,  and 
where  thus  used  the  broken  ends  of  the  blocks  must  be  dressed  to 
make  close  joints.  Unless  otherwise  permitted,  each  course  must  be 
laid  continuously  across  the  street  without  interruption  in  time.  As 
each  course  is  completed  the  end  joints  shall  be  forced  close  together 
by  the  use  of  wedges,  levers  or  mauls.  Upon  the  completion  of 
every  third  course,  the  courses  shall  be  forced  together  by  placing 
a  timber  scantling  against  the  face  of  the  last  course  and  striking  it 
with  a  sledge  or  maul.  When  the  blocks  are  thus  laid,  and  before 


*The  pressure  commonly  specified  is  5000  lt>s.  per  square  inch,  but 
recent  investigations  make  it  doubtful  if  that  pressure  is  ever  attained, 
or  is,  indeed,  practicable  with  any  presses  so  far  constructed. 


37 

the  mortar  under  them  begins  to  set,  they  shall  be  well  rammed  to  a 
solid  bearing  in  the  mortar  with  a  wooden  street  rammer  weighing 
not  less  than  thirty  (30)  pounds,  a  two-inch  plank  ten  (10)  inches 
wide  and  three  (3)  feet  long  being  interposed  between  the  block  and 
the  rammer  and  moved  about  so  that  the  whole  surface  shall  be 
covered  and  rammed.  When  the  ramming  is  completed,  the  top  of 
the  blocks  must  conform  so  closely  to  the  pavement  datum  that  when 
a  template  or  straight  edge  is  placed  upon  the  pavement,  its  surface 
shall  nowhere  depart  from  the  true  surface  more  than  three-six- 
teenths (3-16)  inch.  Blocks,  or  portions  of  the  pavement  found  too 
high  or  too  low,  must  be  taken  up  and  reset  in  fresh  mortar  to  the 
true  grade.  When  thus  completed  to  the  satisfaction  of  the  Engi- 
neer, a  layer  of  one-half  ( % )  inch  of  fine  dry  sand  shall  be  placed 
over  the  surface  and  swept  about  with  brooms  until  all  joints  are 
completely  filled.  The  remaining  sand  shall  be  removed  from  the 
pavement  at  such  time  as  the  Engineer  may  direct. 

When  the  depth  of  the  blocks  exceeds  four  (4)  inches,  they 
may  be  set  upon  a  cushion-course  of  sand,  as  prescribed  for  brick* 
pavement,  Section  88,  the  joints  to  be  filled  with  sand,  as  specified 
above  in  this  Section. 

Railroad  Tracks. 

68.  Where  railroad  tracks  exist  on  the  street  to  be  paved,  the 
construction  shall  be  the  same  as  prescribed  for  granite  block  pave- 
ment, Section  80. 

69.  The  street  shall  not  be  opened  to  travel  until  the  mortar 
under  the  blocks  shall  have  become  fully  set,  and  in  no  case  under 
five  days  after  the  blocks  are  laid. 


GRANITE  BLOCK  PAVEMENT. 

70.  Granite  block  pavement  shall  be  laid  upon  a  foundation 
of  hydraulic  cement  concrete.* 

Sub-Grade  and  Foundation. 

71.  The  sub-grade  shall  be  prepared  as  specified  in  Section  23. 
The  foundation  shall  be  constructed  in  accordance  with  the  require- 
ments of  Sections  25,  26,  27,  28,  29,  30,  31,  32,  33,  34  and  35. 

Granite  Blocks. 

72.  The  blocks  shall  be  made  from  sound,  durable  granite,  of 
uniform  texture,  composition  and  hardness  throughout.     No  outcrop, 
deteriorated,  soft,  brittle,  or  seamy  stone  shall  be  used.     If  the  blocks 
are  obtained  from  different  quarries,  or  from  different  parts  of  the 
same  quarry  where  the  quality  or  appearance  of  the  rock  differs, 
the  product  of  each  must  be  kept  separate  and  laid  together  on  the 
street,  f 

The  blocks  shall  be  not  less  than  eight  (8)  nor  more  than  thir- 
teen (13)  inches  long,  not  less  than  three  and  one-half  (3%) -nor 
more  than  four  and  one-half  ( 4  %  )  inches  wide,  and  not  less  than 
six  and  one-half  (6%)  nor  more  than  seven  (7)  inches  deep.  They 
shall  be  well-shaped,  rectangular,  with  full  edges  and  corners.  Their 
tops  shall  not  depart  more  than  one-half  (  %  )  inch  from  a  true  plane, 
and  their  sides  shall  be  dressed  so  that  joints  between  the  courses 
will  not  be  more  than  three-quarter  (  %  )  inch  wide,  and  their  ends 
so  that  end  joints  shall  not  be  more  than  one-half  (  y2  )  inch  wide.? 
The  size  of  the  blocks  may  be  varied  where  necessary  to  fit  the  pave- 
ment against  or  around  bridge  stones  or  other  street  structures. 

Preparation  of  Foundation. 

73.  The  foundation  shall  be  cleaned  of  all  dirt  and  rubbish. 
There  shall  then  be  spread  evenly  over  it  a  layer  of  clean,  coarse 
sand  to  a  depth  of  one  and  one-half  ( 1  y2  )  inches. 


*Granite  block  pavement  is,  as  a  rule,  used  upon,  and  appropriate 
for  streets  of  the  heaviest  class  of  travel,  and  should,  therefore,  be  pro- 
vided with  the  best  and  strongest  foundation.  It  is  nearly  always 
poor  economy  to  lay  granite  blocks  upon  a  broken  stone,  gravel,  or 
sand  foundation. 

tLike  other  stones,  granite  from  various'  localities  differs  widely 
in  strength,  hardness  and  brittleness.  Great  hardness,  accompanied  with 
comparative  brittleness,  is  not  desirable  in  granite  for  paving  blocks. 
Such  material  usually  polishes  by  travel  and  becomes  quite  slippery, 
and  it  is  likely  to  become  "turtle-backed,"  that  is,  the  corners  are 
likely  to  be  chipped  off  or  worn  off,  making  the  pavement  very  rough 
and  uneven. 

$As  a  rule,  the  closer  the  joints  are  made,  the  less  likely  are  the 
paving  blocks  to  become  "turtle-backed,"  and  the  more  likely  is  the 
pavement  to  wear  down  evenly,  thus  preserving  an  even  and  compar- 
atively smooth  surface. 


UNIVERSITY 

or 


Sotting  the  Blocks. 

74.  The  blocks  shall  be  set  in  this  bed  of  sand  perpendicular 
to  the  street  surface,  with  their  length  at  right  angles  to  the  street, 
in  courses  extending  entirely  across  the  street,  and  at  right  angles 
to  its  axis,  except  at  street  intersections  where  the  courses  shall  be 
set  at  such  angle  with  the  street  as  the  Engineer  may  direct.     Only 
stones  of  the  same  width  shall  be  set  in  the  same  course.      The 
stones  in  each  course,  and  in  adjoining  courses,  shall  be  set  firmly 
against  each  other.     The  blocks  shall  be  set  in  the  sand  bed  in  such 
a  manner  that  their  tops  shall  be  even  with  each  other  and  to  such 
an   elevation   that   after   the   pavement   is   rammed,   as   hereinafter 
directed,  its  general  surface  shall  conform  closely  to  the  grade  and 
contour   designed   for  the   pavement.      Stones   in   adjoining   courses 
shall  break  joint  not  less  than  three  (3)   inches. 

Hamming. 

75.  After  the  blocks  are  set  they  shall  be  thoroughly  rammed 
to  give  them  a  firm  bearing  in  the  sand  and  to  bring  their  tops  to 
the    prescribed    pavement    datum.      The    rammers    used    shall    have 
wooden  faces,  or,  if  rammers  with  iron  faces  are  used,  a  two-inch 
plank,  one  foot  wide  and  three  feet  long,  shall  be  interposed  between 
the  blocks  and  the  rammers.      The  rammers  shall   weigh  not  less 
than  thirty  (30)   pounds.     Blocks  or  sections  of  blocks  wrhose  tops 
under  the  ramming  remain  above  or  sink  below  the  pavement  datum 
shall  be  taken  up  and  reset  so  that  after  the  ramming  is  completed 
their  tops  shall  coincide  with  the  pavement  datum. 

Filling  the  Joints.* 

76.  After  the  ramming  specified  in  Sect.   75  shall  have  been 
completed,  the  joints  between  the  paving  blocks  shall  be  filled  in  the 
following  manner: 

All  the  joints  for  a  distance  of  three  feet  out  from  the  curb- 
stones, and  three  contiguous  joints  continuous  across  the  street,  with 
the  included  end  joints,  at  intervals  of  about  fifty  (50)  feet  in  the 
length  of  the  street,  shall  be  filled  with  gravel  and  bituminous 
paving  cement.  The  gravel  used  shall  be  of  such  size  that  all  will 
pass  through  a  screen  having  five-eighths  ( % )  inch  meshes,  and 
all  will  be  held  on  a  screen  having  one-fourth  ( *4 )  inch  meshes. 
When  used,  the  gravel  must  be  free  from  refuse  and  street  dirt. 
The  bituminous  paving  cement  shall  be  composed  of  straight-run 
coal  tar  pitch  of  the  hardness  commonly  known  as  number  six,  to 


*It  has  been  the  almost  universal  custom,  in  this  country  at  least, 
to  fill  the  joints  in  granite  paving  with  gravel  and  bituminous  pitch. 
But  the  reasons  that  have  led  engineers  to  prefer  grout  filling  for  brick 
pavements  apply  with  equal  force  to  granite  pavement.  It  makes  a 
stronger  and  harder  filling  than  the  gravel  and  bituminous  cement,  and 
gives  a  better  support  to  the  edges  of  the  paving  blocks,  thus  tending 
to  prevent  chipping  and  "turtle-backing"  in  the  pavement.  It  is  also 
a  materially  cheaper  filling  than  the  gravel  and  bituminous  cement. 
But  to  provide  for  the  expansion  and  contraction  of  the  pavement  by 
changes  of  temperature,  it  is  desirable  that  a  strip  in  the  gutters,  and 
an  occasional  strip  across  the  whole  street,  shall  be  filled  with  the  more 
yielding  material. 


40 

which  has  been  added  and  thoroughly  mixed,  while  both  are  in  a 
melted  condition,  twenty  per  cent.  (20%)  by  weight  of  refined 
Trinidad  asphalt,  or  other  asphalt,  equal  for  the  purpose,  and 
twenty  per  cent.  (20%)  by  weight  of  Portland  cement.  These 
ingredients  must  be  thoroughly  mixed,  and  kept  agitated  until  used.* 

The  joints  will  first  be  filled  with  the  gravel,  perfectly  dry, 
and  heated  so  that  when  put  in  the  joints  it  will  be  at  a  temperature 
of  about  three  hundred  (300)  degrees  F.  The  paving  cement,  heated 
to  a  temperature  of  about  two  hundred  and  fifty  (250)  degrees  F., 
shall  be  at  once,  while  the  gravel  is  still  hot,  poured  from  a  spouted 
vessel  into  the  joints  until  the  interstices  of  the  gravel  are  entirely 
filled  to  the  surface  of  the  pavement,  repouring  being  resorted  to 
to  accomplish  this  result. 

All  the  joints  in  the  pavement  other  than  those  named  above 
shall  then  be  completely  filled  with  Portland  cement  grout,  as 
follows: 

The  grout  shall  be  composed  of  equal  parts  by  volume  of  sand 
(Sect.  27)  and  Portland  cement  (Sect.  26),  a  quick-setting  cement 
being  preferred.  The  sand  and  cement  shall  be  first  thoroughly 
mixed  dry  and  then  enough  water  added  to  make  a  grout  of  such 
consistency  that  it  will  flow  like  thick  cream,  and  the  mixing  con- 
tinued until  a  homogeneous  mass  is  produced  and  until  the  grout  is 
applied  to  the  pavement.  The  grout  shall  be  prepared  in  water- 
tight boxes  of  a  convenient  size.  Before  applying  the  grout  the 
the  pavement  shall  be  thoroughly  dampened  by  sprinkling.  The 
grout  shall  be  removed  from  the  mixing  box  and  spread  over  -the 
pavement  with  scoop  shovels,  in  two  courses,  the  first  being  suf- 
ficient to  about  half  fill  the  joints,  and  the  second,  which  shall  be 
applied  before  the  first  has  begun  to  set,  shall  be  sufficient  to 
entirely  fill  the  remaining  space  in  the  joints.  As  rapidly  as  the 
grout  is  applied  it  shall  be  swept  about  with  brooms  until  it  all 
enters  the  joints. 

Order  of  Work. 

77.  The  sand  bed  shall  not  be  put  in  place  more  than  fifty 
(50)  feet  ahead  of  the  block  setters.  The  ramming  and  filling  of  the 
joints  shall  follow  closely  the  block  setting,  but  no  ramming  shall 
be  done  within  less  than  six  (6)  feet  of  the  face  of  the  block  setting; 
and  the  final  joint  filling  shall  be  kept  completed  to  within  twenty- 
five  (25)  feet  of  the  ramming;  but  all  the  work  rammed  during  any 
day  shall  have  the  joint  filling  completed  before  the  cessation  of 
work  on  that  day.  The  street  shall  not  be  opened  to  travel  until 
the  grout  has  thoroughly  set. 


*The  object  of  adding-  asphalt  and  Portland  cement  is  to  make  the 
cement  stronger  and  less  susceptible  to  changes  of  temperature.  Pure 
coal-tar  pitch  is  very  brittle  at  low  temperatures,  and  is  liable  to 
flow  from  the  crown  of  the  street  to  the  gutters  in  hot  summer 
weather.  A  cement  made  as  here  specified  is  not  only  much 
stronger  and  less  brittle  in  cold  weather,  but  requires  a  materially 
higher  temperature  to  cause  it  to  flow  than  does  pure  pitch. 


41 

Fitting  Paving  Around  Other  Structures. 

79.  The  size  of  blocks  and  the  width  of  courses  shall,  as  the 
block  laying  approaches  bridge  stones,  curbs  and  other  structures, 
or  in  making  closures  with  other  sections  of  pavement,  be  so  selected 
and  adjusted  that  joints  not  over  three-quarters  (  %  )  inch  in  width 
shall  result,  without  breaking  blocks  or  splitting  courses. 

Street  Railroad  Tracks. 

80.  Where  railroad  tracks  exist  in  the  street  the  paving  blocks 
shall  be  laid  against  the  rail  in  the  following  manner: 

The  sub-grade  and  the  pavement  foundation  shall  extend  under 
the  rails  uninterrupted  except  by  the  ties  or  other  structures  con- 
nected with  the  railroad  track.  For  a  distance  of  fourteen  (14) 
inches,  on  each  side  of  the  rail,  measuring  from  the  center  thereof, 
there  shall  be  spread  on  the  pavement  foundation  a  layer  of  mortar 
not  less  than  one  and  one-half  ( 1  % )  inches  thick,  composed  of  one 
(1)  part  of  cement  and  three  (3)  parts  sand,  complying  with  the 
requirements  of  Sections  26  and  27.  Upon  this  layer  of  mortar  shall 
be  set,  against  the  rail,  and  on  each  side  of  it,  selected  paving 
blocks,  securely  bedded  in  the  mortar  before  it  shall  have  begun  to 
set.*  Alternate  blocks  shall  be  long  and  short  so  as  to  break  joint 
with,  the  blocks  of  the  adjoining  pavement.  Selected  blocks  with 
well  dressed  top  surfaces  shall  be  used  and  their  tops  shall  be  set 
as  nearly  as  practicable  at  the  level  of  the  top  of  the  rail,  but  not  so 
high  that  the  car  wheels  will  ride  upon  them.  In  setting  the  blocks 
they  shall  be  firmly  bedded  into  the  mortar  by  the  use  of  paving 
hammers,  but  they  shall  not  be  thereafter  rammed.  As  the  blocks 
are  set,  any  space  between  the  paving  blocks  and  the  web  of  the  rail 
shall  be  filled  with  mortar  of  the  quality  described  above.  The 
placing  of  these  blocks  shall  not  precede  by  more  than  ten  (10) 
feet  the  block  laying  on  the  street.  Care  must  be  taken  not  to 
disturb  the  bedding  of  these  blocks  in  the  laying  of  the  adjoining 
pavement,  or  otherwise.  The  joints  shall  be  filled  in  the  same 
manner  as  prescribed  for  the  other  portions  of  the  pavement. 

The  construction  along  slot-rails  shall  be  the  same  as  described 
above,  except  that  blocks  of  special  size  or  shape  may  be  required, 
as  the  Engineer  may  direct. 

Bridge  Stone  Crossings. 

81.  Where   directed   by   the   Engineer,   the   old   bridge   stone 
shall  be  redressed  and  relaid,  as  hereinafter  specified  for  new  bridge 
stone,  and  shall  be  moved  from  the  point  where  taken  up  to  the 
point  where  they  are  to  be  relaid,  by  the  Contractor  at  his  expense. 

New  bridge  stone  shall  be  of  the  same  quality  of  granite  as  the 
paving  blocks  and  free  from  imperfections.  They  shall  not  be  less 


•As  the  wheels  of  vehicles  frequently  follow  along  the  lines 
of  the  rails,  thus  concentrating  their  effect  on  a  narrow  strip  near  the 
rails,  and  as  the  continuous  joint  against  the  rail  makes  the  pavement 
weaker  there,  the  mortar  bed,  and  the  greater  care  in  setting  the  blocks 
along  and  near  the  rail  are  advisable. 


42 

than  three  and  one-half  (3%)  nor  more  than  six  (6)  feet  long, 
eighteen  (18)  inches  wide  and  of  a  uniform  thickness  not  less  than 
six  (6)  nor  more  than  eight  (8)  inches,  but  these  dimensions  may 
be  varied  by  the  Engineer  where  necessary  to  fit  the  stone  into 
special  locations. 

Their  top  shall  be  well  dressed  to  a  true  plane  surface  not  vary- 
ing in  evenness  more  than  one-quarter  (  ^4  )  inch.  The  sides  shall 
be  dressed  perpendicular  to  the  face  so  as  to  joint  closely  against 
the  paving  blocks,  and  the  ends  shall  be  so  dressed  and  to  such  a 
bevel  that  when  set  in  the  curved  surface  of  the  street,  the  joint 
between  adjoining  stones  shall  not  be  wider  than  one-quarter  (  %  ) 
inch  from  top  to  bottom. 

Bridge  stones  shall  be  set  in  advance  of  the  block  laying,  over 
the  street  foundation,  in  a  bed  of  sand  or  gravel  in  which  they  shall 
be  firmly  bedded.  Their  upper  surface  shall  conform  truly  to  the 
pavement  datum.  They  shall  be  set  accurately  to  the  lines  given 
by  the  Engineer.  Where  the  crosswalk  requires  more  than  one 
course  of  bridge  stone,  the  courses  shall  be  laid  parallel  to,  and  at 
such  distance  from  each  other  as  the  Engineer  may  direct,  and  the 
space  between  courses  shall  be  filled  with  paving  blocks  laid  as 
specified  in  Sections  74,  75,  76  and  77. 


BRICK    PAVEMENT.* 

Sub-Grade. 

82.  The  sub-grade  for  brick   pavement  shall  be  prepared   in 

accordance  with  Sect.  23  and  shall  be  finished  to  a  surface 

inches  below  and  parallel  to  the  pavement  datum. 

Foundation. 

83.  The  foundation  for  brick  pavement  shall  be  of 

t  prepared   in   accord- 
ance with  Sections 

Its  thickness  shall  be inches  and  its  upper  surface 

shall,  when  completed,  be  parallel  to  and  at  a  depth  below  the  pave- 
ment datum  equal  to  the  depth  of  the  brick  plus  one  and  one-fourth 
( 1 14 )   inches.     The  surface  of  the  foundation  shall  not  vary  more 
than  one-half  (  % )  inch  above  or  below  that  depth. 

Paving  Brick. 

84.  The  linear  dimensions  of  paving  brick  may  vary  between 
the  following  limits:    In  length,  from  eight  and  one-half   (8%)    to 
nine  and  one-half  (9%)  inches;  in  width,  from  two  and  one-fourth 
(2*4)  to  three  and  one-half  (3%)  inches;   in  depth,  from  four  (4) 
to  four  and  one-eighth    (4%)    inches;    but  the  length  shall  not  be 
less  than  three    (3)    nor  more  than  three  and  three-fourths    (3%) 
times  the  width.     The  corners  shall  all  be  rounded  off  to  a  radius 
of   not  less  than   one-eighth    ( % )    nor   more   than   three-sixteenths 
(3-16)  inch.     The  brick  for  any  one  contract  shall  be  all  of  the  same 
kind  and  of  the  same  standard  size,  and  the  individual  bricks  shall 
not  vary  in  length  more  than  three-sixteenths   (3-16)   inch,  nor  in 
width  more  than  one-eighth    ( % )    inch  from   the  size  adopted   as 
standard. 

The  brick  must  be  specially  manufactured  for  paving  purposes. 
They  may  be  made  from  shale  or  from  suitable  clay.  In  either  case 
the  material  must  be  thoroughly  pulverized,  mixed  and  tempered, 
and  must  be  free  from  lime  nodules  or  other  substances  that  may 
disintegrate  the  brick  when  immersed  in  water.  The  brick  shall  be 
molded  in  efficient  brick  machines  and  repressed  to  a  truly  rect- 
angular form,  free  from  cracks,  flaws  and  injurious  laminations. 
After  being  properly  dried  the  brick  shall  be  properly  and  uniformly 
burned  in  down-draft  kilns.  Shale  brick  shall  be  burned  to  the 


*The  specifications  here  given  for  brick  pavement  follow  closely  the 
lines  which  experience  has  dictated,  and  conform  closely  to  those  rec- 
ommended by  the  National  Brick  Manufacturers'  Association. 

tHere  again  a  good  concrete  foundation  is  recommended,  as  being 
in  the  end  the  most  satisfactory  and  economical.  See  foot-note,  page  15. 


44 

point  of  incipient  fusion  or  vitrification.  After  the  burning  is  com- 
pleted the  brick  shall  be  allowed  to  cool  with  sufficient  slowness 
to  insure  thorough  annealing. 

The  completed  brick  shall  be  free  from  flaws,  cracks,  ragged 
corners,  and  from  such  distortion  or  warping  as  will  interfere  with 
their  utility  or  good  appearance  in  the  pavement.  Paving  brick 
shall  not  be  salt-glazed. 

85.  The   brick   shall   be   subjected   to   the   following   tests   to 
determine  their  quality: 

When  broken  by  the  blows  of  a  hammer  the  brick  shall  be 
strong  and  tough.  The  broken  surface  shall  show  a  homogeneous 
composition  throughout  the  broken  section,  free  from  flaws,  injur- 
ious laminations,  nodules  and  voids,  and  shall  appear  to  be  uniformly 
burned  from  surface  to  center. 

When  subjected  to  the  standard  "Rattler"  test,  in  accordance 
with  the  rules  adopted  by  the  National  Brick  Manufacturers'  Asso- 
ciation, the  average  loss  in  weight  shall  not  exceed  eighteen  (18) 
per  cent.,  and  the  loss  in  weight  of  any  individual  brick  in  the  test 
shall  not  be  more  than  twenty-five  (25)  per  cent,  greater  than  the 
average  loss  of  the  whole  charge. 

When  subjected  to  the  absorption  test,  in  accordance  with  the 
rules  adopted  by  the  National  Brick  Manufacturers'  Association, 
shale  bricks  shall  not  absorb  more  than  two  (2)  per  cent,  nor  less 
than  one-half  (  %  )  of  one  per  cent,  of  their  weight  of  water,*  and 
clay  bricks  shall  not  absorb  more  than  six  (6)  per  cent,  of  their 
weight  of  water;  the  absorption  of  any  individual  brick  shall  not 
be  more  than  fifty  (50)  per  cent,  greater  than  the  mean  absorption 
of  the  whole  lot  tested.  Brick  that  do  not  successfully  pass  all  these 
tests  will  not  be  accepted. 

Samples. 

86.  Where  samples  of  paving  brick  have  been  required  and 
submitted  by  successful  bidders,  and  tested  as  described  above,  it 
will  be  assumed  that  these  samples  fairly  represent  the  quality  of 
the  brick  to  be  subsequently  supplied  for  the  work,  and  brick  that 
do  not  come  up  to  the  standard  thus  established  will  not  be  accepted. 

Delivering  Brick  on  Street. 

87.  Unless  the  sidewalks  are  too  narrow  to  permit  of  it,  the 
brick  shall  all  be  delivered  upon  the  street  before  the  foundation  is 
constructed,  and  neatly  piled  upon  the  outer  edge  of  the  sidewalks, 
occasional  openings  being  left  in  the  piles  for  the  accommodation 
of  foot  passengers.     One-half  the  brick  required  shall  be  thus  deliv- 
ered and  piled  upon  each  sidewalk.     In  delivering  the  bricks  from 
these  piles  to  the  bricklayers,  they  must  be  carried  on  pallets,  or 


*Absorption  of  less  than  one-half  of  one  per  cent,  usually  indicates 
that  a  shale  brick  has  been  over-burned,  resulting-  in  increased  brittle- 
ness. 


other  suitable  devices  must  be  used;  they  must  not  be  dumped  from 
wheelbarrows  upon  the  freshly-laid  brick  pavement. 

If  for  any  reason  the  bricks  are  not  delivered  before  the  foun- 
dation is  laid,  or  if  the  sidewalks  are  too  narrow  to  permit  of  the 
brick  being  stored  upon  them,  they  may  be  delivered  over  the  foun- 
dation, but  not  until  the  concrete  has  set  so  hard  that  it  will  not  be 
injured  by  transportation  over  it. 
Sand  Cushion. 

88.  Directly  before  the  brick  are  laid  into  the  pavement  there 
shall  be  spread  over  the  foundation  a  layer  of  sand  one  and  one-half 
( 1  %  )   inches  in  depth.     The  sand  shall  be  free  from  vegetable  or 
other  refuse  matter,  and  shall  not  contain  more  than  five   (5)   per 
cent,  of  clay  and  loam.     Pebbles  and  fragments  of  stone  exceeding 
one-half  inch  in  diameter  must  be  screened  out.     When  spread  on 
the  street  the  sand   shall   be  sufficiently  dry  to   permit  of   proper 
gaging  by  templates,  as  hereinafter  described.     The  sand  shall  be 
spread  and  correctly  gaged  to  the  proper  thickness  and  surface  by 
the  use  of  templates  formed   to   the  true  designed   cross-sectional 
contour  of  the  pavement.     If  the  width  of  the  street  between  curbs 
does  not  exceed  twenty-five   (25)   feet,  the  template  shall  be  made 
in  one  length  sufficient  to  cover  the  full  width  of  the  street,  and  its 
ends  shall  be  so  constructed  and  fitted  with  iron  rollers,  that  it  will 
rest  upon  and  roll  along  the  top  of  the  curb  at  each  end;   if  the 
width  of  the  street  between  curbs  be  not  more  than  fifty  (50)   feet 
the    template    shall    be    of    sufficient    length    to    reach    from    the 
curb  to  the  middle  of  the  street,  and  constructed  to  move  on  rollers 
on  top  of  the  curb  at  one  end  and  upon  a  plank  six  (6)  inches  wide 
and  one  and  one-half  (1%)   inches  thick  laid  upon  the  foundation 
along  the  center  line  of  the  pavement.   The  template  shall  be  worked 
forwards  and  backwards  along  the  line  of  the  street  until  the  surface 
of  the  sand  conforms  exactly  to  the  designed  contour  of  the  pave- 
ment, at  a  depth  below  the  pavement  datum  equal  to  the  depth  of 
the  paving  brick  minus  one-fourth  ( *4 )  inch.     When  completed  the 
surface  of  the  sand  cushion  shall  be  smooth  and  unbroken,  and  care 
must  be  taken  not  to  disturb  it  before  the  bricks  are  set  upon  it. 

Setting  the  Brick. 

89.  Several   courses   of   brick,    aggregating   a   strip   having   a 
width  of  not  less  than  twelve  (12)  inches  nor  more  than  fifteen  (15) 
inches  on  each  side  of  the  street,  beginning  against  the  curb,  shall 
be  first  laid,  the  brick  being  set  with  their  long  dimension  parallel 
to    the    curb.*      The    pavement    intervening    between    these    gutter 
courses  will  then  be  set  in  courses  at  right  angles  to  the  axis  of 
the  street,   except  in  street   intersections,   where  the   courses   shall 
make  an  angle  of  forty-five  (45)  degrees  with  the  axis  of  the  street. 
The  brick  shall  be  set  upon  edge  on  the  sand  cushion  with  their 

*The  object  of  this  is  to  make  a  gutter  offering  less  obstruction  to 
the   flow  of  water. 


46 

faces  parallel  to  the  pavement  datum,  in  straight  courses,  continuous 
across  the  street,  the  long  dimension  of  the  brick  being  parallel  to 
the  courses;  they  shall  be  set  as  closely  together  as  possible,  so  that 
the  joints  both  between  the  courses  and  between  individual  bricks 
shall  not  exceed  one-eighth  ( y8 )  inch.  Broken  bricks  and  bats 
shall  not  be  used  except  as  closures  at  the  ends  of  the  course  and 
in  fitting  the  pavement  around  manholes,  etc.,  and  nothing  smaller 
than  half-bricks  shall  be  used  in  either  case,  and  the  broken  ends 
must  be  shaped  to  make  reasonably  close  joints. 
Inspection. 

90.  After  the  bricks  are  laid  the  pavement  will  be  inspected 
by  the  Engineer,  or  his  agent.      He  may   require  that  the  surface 
shall  be  previously  wetted  by  sprinklers,  or  by  a  sprinkling  nozzle, 
in  order  to  detect  soft  or  porous  bricks.*     Defective  bricks  indicated 
by  him  shall  be  removed  and  replaced  by  acceptable  brick. 

Rolling  and  Ramming. 

91.  The   surface    of    the   pavement   shall   then    be   rolled    and 
rammed  in  the  following  manner: 

The  roller  used  shall  be  of  the  asphalt  roller  style,  driven  by 
steam  and  weighing  not  less  than  three  and  one-half  ( 3  l/2  )  nor  more 
than  five  (5)  tons.  The  rolling  shall  begin  as  near  the  curb  as 
practicable,  the  roller  being  operated  slowly,  parallel  to  the  axis 
of  the  street,  and  working  outwardly  until  the  center  of  the  street 
is  reached,  when  the  roller  will  proceed  to  the  opposite  side  of  the 
street  and  the  operation  proceed  as  before.  After  this  longitudinal 
rolling  is  completed  the  pavement  will  be  continuously  rolled  a 
second  time,  the  roller  operating  back  and  forth  at  an  angle  of 
forty-five  degrees  to  the  axis  of  the  street,  and  a  third  time,  the 
roller  operating  at  right  angles  to  the  course  of  the  second  rolling. 
After  the  rolling  is  thus  completed  the  brick  in  the  gutters  not 
reached  by  the  roller  shall  be  rammed  with  a  street  rammer  weigh- 
ing not  less  than  fifty  (50)  pounds,  a  plank  not  less  than  six  (6) 
feet  long,  ten  (10)  to  twelve  (12)  inches  wide  and  two  (2)  inches 
thick  being  interposed  between  the  pavement  and  the  rammer  and 
moved  about  so  that  the  whole  surface  of  the  gutter  shall  be  thor- 
oughly and  equally  rammed  and  its  surface  brought  to  an  even 
junction  with  the  rolled  portion  of  the  work. 

When  the  rolling  and  ramming  is  thus  completed  the  surface 
of  the  pavement  shall  conform  so  truly  to  the  designed  pavement 
datum  that  it  will  nowhere  depart  more  than  three-sixteenths  (3-16) 
inch  from  properly-formed  templates  and  straight-edges  applied  to 
its  surface. 
Filling  the  Joints. 

92.  Directly  after  the  completion  of  the  rolling  and  ramming, 
the  joints  between  the  bricks  shall  be  filled  as  follows: 


*This    is    the    simplest    and    most    effective   way    to    detect    soft    and 
underburned  brick. 


47 

The  joints  in  the  longitudinal  gutter  courses,  and  the  joints 
between  six  contiguous  courses  running  across  the  street,  from 
gutter  to  gutter,  in  each  length  of  fifty  (50)  feet  of  the  pavement, 
shall  be  filled  with  bituminous  cement  composed  of  coal-tar  pitch, 
commercially  known  as  Number  Six,  to  which  has  been  added 
fifteen  (15)  per  cent,  of  refined  Trinidad  asphalt  and  twenty  (20) 
per  cent,  of  hydraulic  cement,  all  by  weight.*  In  preparing  this 
bituminous  cement,  the  pitch  shall  first  be  melted  and  the  asphalt, 
also  melted,  added  and  thoroughly  incorporated  by  agitation.  The 
hydraulic  cement  shall  then  be  added  and  the  whole  agitated  until 
a  complete  and  uniform  mixture  results.  The  bituminous  cement 
thus  prepared  shall  be,  while  sufficiently  hot  and  liquid  to  flow 
freely,  poured  from  a  spouted  vessel  into  the  joints  until  they  appear 
to  be  nearly  or  quite  full.  After  allowing  time  for  the  filling  to 
subside,  the  joints  will  be  gone  over  a  second  time  and  completely 
filled,  care  being  taken  to  confine  the  cement  to  the  joints  and  not 
to  deposit  it  on  the  surface  of  the  pavement. 

All  the  remaining  joints  in  the  pavement  shall  be  filled  with 
Portland  cement  grout,  as  follows: 

The  grout  will  be  composed  of  equal  parts  by  volume  of  sand 
(Sect.  27)  and  Portland  cement  (Sect.  26),  a  quick-setting  cement 
being  preferred.  The  sand  and  cement  shall  be  first  thoroughly 
mixed  dry  and  then  enough  water  added  to  make  a  grout  of  such 
consistency  that  it  will  flow  like  thick  cream,  and  the  mixing  con- 
tinued until  a  homogeneous  mass  is  produced  and  until  the  grout 
is  applied  to  the  pavement.  The  grout  shall  be  prepared  in  water- 
tight boxes  of  a  convenient  size.  Before  applying  the  grout  the 
pavement  shall  be  thoroughly  dampened  by  sprinkling.  The  grout 
shall  be  removed  from  the  mixing  box  and  spread  over  the  pavement 
with  scoop  shovels,  in  two  courses,  the  first  being  sufficient  to  about 
half  fill  the  joints,  and  the  second,  which  shall  be  applied  before  the 
first  has  begun  to  set,  shall  be  sufficient  to  entirely  fill  the  remaining 
space  in  the  joints.  As  rapidly  as  the  grout  is  applied  it  shall  be 
swept  about  with  brooms  until  it  all  enters  the  joints. f 

93.  Travel  must  be  excluded  from  the  pavement  until  the 
grout  has  set  firmly;  in  no  case  less  than  five  days. 

*See  foot-note,  page  40. 

tThe  bituminous-cement  joints  are  principally  for  the  purpose  of 
providing  for  the  expansion  of  the  pavement  in  very  hot  weather. 

•  Experience  seems  to  have  proved  that  cement  grout  is,  everything 
considered,  the  best  and  cheapest  filling  for  the  joints  in  brick  pave- 
ment. If  the  filling  is  properly  done,  the  edges  of  the  brick  are  sup- 
ported and  the  corners  do  not  chip  off.  With  the  expansion  joints  pro- 
vided at  intervals  by  the  bituminous-filled  joints,  the  curbs  will  not  be 
forced  out  of  line,  nor  will  the  pavement  be  raised  from  its  sand  bed  by 
expansion,  causing  the  rumbling  sound  sometimes  noticed. 


48 


WOOD-BLOCK   PAVEMENT. 
Sub-Grade. 

94.  The  sub-grade  for  wood-block  pavement  shall  be  prepared 
as    specified    in    Section    23,    and    shall    be    finished    to    a    surface 
inches  below  the  pavement  datum. 

Foundation. 

95.  The   foundation   for  wood-block   pavement  shall  be  Port- 
land   cement    concrete inches    thick,    prepared    as 

specified  in  Sections  25,  26,  27,  28,  29,   30,   31,   32,   33,   34   and  35. 
The  upper  surface  of  the  concrete  foundation,  when  completed,  shall 
be  at  a  distance  below  the  pavement  datum  equal  to  the  depth  of 
the  blocks  to  be  laid,  plus  one-half   (  y2  )    inch,  and  must  not  vary 
more  than  one-fourth  (  ^4  )  inch  above  or  below  that  depth. 

MATERIALS. 

Wood-Blocks. 

96.  The  wood-blocks  shall  be  of  Southern  long-leaved  Yellow 
Pine,  Loblolly  Pine  of  slow  growth,  White  Oak,   Chestnut  or  Red 
Oak,  White  Elm,  Red  Gum,  or  other  species  of  wood,  which,  in  the 
opinion  of  the  Engineer,  are  equally  as  strong  and  durable  as  those 
named,  and  of  a  texture  permitting  satisfactory  preservative  treat- 
ment, as  hereinafter  specified;  but  all  the  blocks  for  any  one  contract- 
shall  be  of  the  same  species  of  wood.*     Only  wood  from  live,  sound 
trees  shall   be   used.      The  lumber   from   which  the   blocks  are  cut 
shall  be  properly  manufactured,  free  from  bark,  and  with  full  square 
corners.     It  shall  be  free  from  decay,  dotiness,  brashness,  shakes, 
large  season  cracks,  loose  or  unsound  knots  over  three-  fourths  (  %  ) 
inch   in   diameter,    and   all   other   imperfections   which   may,    in   the 
opinion  of  the  Engineer,  be  detrimental.     "Fat"  pine  containing  so 
much  resin  that  it  will  not  take  up  the  specified  quantity  of  creosote 
oil    in    treatment    may    be    rejected.       Second-growth    timber,    and 
Southern  pine  showing,  outside  of  a  radius  of  three  (3)  inches  from 
the  heart,  ten  (10)  or  less  annual  growth  rings  to  the  inch,  will  not 
be  accepted 


*Since  immunity  from  early  natural  decay  is  secured  by  preserva- 
tive treatment,  the  important  requisite  for  wood  paving-  blocks  is  ca- 
pacity to  withstand  the  wear  and  tear  of  the  travel  on  the  street.  We 
have  no  very  satisfactory  data  as  to  the  ability  of  the  various  species 
of  wood  to  endure  the  somewhat  peculiar  and  special  duty  to  which 
paving  blocks  are  subjected. 

The  test  which  seems  to  most  nearly  approach  to  what  is  wanted 
is  that  of  crushing  strength,  when  the  force  is  applied  to  the  end  of  the 
sample,  parallel  to  its  fibers;  but  this  does  not  embrace  the  effect  of 
impact  to  which  paving  blocks  are  subjected  under  street  travel.  Wheth- 
er this  may  be  considered  a  function  of  the  end-crushing  strength  or 


49 

The  paving  blocks,  cut  from  the  lumber  above  specified,  shall 
be  well  manufactured,  truly  rectangular  and  of  uniform  dimensions. 

Their  depth,  (parallel  to  the  fiber)  shall  be. inches,* 

their  length  shall  be  not  less  than  seven  (7)  nor  more  than  twelve 
(12)  inches,  and  their  width  shall  be  not  less  than  three  (3)  nor 
more  than  four  (4)  inches;  but  all  the  blocks  for  any  one  contract 
shall  be  of  the  same  depth  and  width.  Their  depth  and  width  shall 
not  vary  more  than  one-eighth  (  %  )  inch  from  the  dimensions  speci- 
fied. 

Creosote  Oil. 

97.  The  oil  used  for  preservative  treatment,  commercially 
known  as  creosote  oil,  shall  be  Dead  Oil  of  Coal  Tar,  without  adul- 
teration. Oil  known  to  the  trade  as  "Wood  Creosote  Oil"  will  not 
be  accepted.  The  dead  oil  of  coal  tar  shall  not  contain  more  than 
one  and  one-half  ( 1  % )  per  cent,  of  water,  nor  more  than 
5%  of  tarry  matter.  Its  specific  gravity,  at  60  degrees  F.,  shall 
not  be  below  1.02  nor  above  1.07.  Subjected  to  distillation  no  part 


not  is  an  open  question,  though  there  seems  good  reason  to  believe 
that  it  will  prove  to  be  so;  and  if  so,  there  is  no  good  reason  why  woods 
of  substantially  equal  strength  under  the  end-crushing  test  should  not 
show  about  the  same  endurance  under  street  travel,  independent  of  the 
element  of  natural  durability,  which  is  practically  eliminated  by  preserv- 
ative treatment.  The  most  complete  set  of  tests  of  the  endwise  com- 
pression of  different  species  of  wood  yet  available  to  the  engineer,  is 
that  made  under  the  direction  of  the  Division  of  Forestry,  U.  S.  Dept. 
of  Agriculture,  the  results  of  which  were  published  in  Circular  Number 
15,  of  that  Division.  The  average  strength,  in  a  dry  condition,  under 
endwise  compression,  of  the  several  woods  enumerated  as  acceptable  in 
these  specifications,  is  given,  as  follows: 

Southern    Long-Leaved    Yellow    Pine 6900 

Loblolly    Pine     6500 

White     Oak 8500 

Chestnut     Oak 7200 

Red     Oak 7200 

White    Elm    6500 

Red    Gum     7100 

Other  species  of  the  oak  family,  as  Overcup  Oak,  Burr  Oak,  Post 
Oak,  Spanish  Oak  and  Water  Oak.  all  show  a  resistance  to  end  crush- 
ing of  over  7000  pounds  per  square  inch.  In  the  absence  of  even  presump- 
tive reasons  to  the  contrary,  and  in  the  absence  of  actual  experience, 
it  is  reasonable  to  conclude  that  all  these  woods  can  be  safely  used,  after 
proper  preservative  treatment,  for  street  paving  purposes.  The  Red 
Gum  (Liquidambar  Styraciflual),  more  commonly  known  in  the  middle 
Mississippi  valley  as  Sweet  Gum,  seems  to  possess  qualities  that  make 
It  peculiarly  suitable  for  street  paving  blocks,  and  its  comparative 
cheapness,  compared  with  Yellow  Pine  and  the  oaks,  is  a  strong  recom- 
mendation. 

There  seems  to  be  no  good  reason  why  Long-Leaved  Yellow  Pine 
should  alone  be  specified  as  acceptable,  as  it  has  been  in  most  cases 
heretofore,  particularly  as  the  lumber  now  marketed  under  that  name 
almost  always  contains  a  large  percentage  of  short-leaved  or  bastard 
pine,  a  distinctly  inferior  wood. 

*The  question  of  the  most  economical  depth  for  wood  paving  blocks 
is  as  yet  unsettled.  In  New  York  City,  blocks  3  1-2  inches  in  depth 
are  adopted  as  the  standard  and  are  being  used  on  streets  of  the  heav- 
iest travel,  the  practice  of  Berlin,  Paris  and  other  foreign  cities  being 
thus  followed.  The  arguments  in  favor  of  these  short  blocks  are 
lower  first  cost,  and  that,  with  much  deeper  blocks,  the  usual  uneven 
wear  of  a  wood  pavement  will  make  it  so  rough  as  to  require  removal 
before  the  blocks  are  worn  down  so  as  to  be  split  up  and  dislodged 
from  their  places.  While  reliable  data  on  these  points  are  wanting,  it 
seems  to  the  writer  very  unwise  to  use  such  short  blocks  on  streets 
of  heavy  travel,  and  he  would  recommend  that  the  minimum  length 
for  use  on  such  streets  be  4  1-2  inches,  and  he  would  prefer  5  inches. 

On  streets  of  light  travel  a  length  of  3  1-2  inches  should  be  sat- 
isfactory. 


50 

of  it  shall  be  volatile  at  a  temperature  of  300  degrees  F.,  and  it  snail 
not  lose  by  evaporation  more  than 20%  in  weight  when  maintained  at 
a  temperature  of  400  degrees  F.  for  four  (4)  hours.  With  increased 
temperature  it  shall  yield  not  less  than  4h%  nor  more  than  55% 
of  naphthaline.  The  residue,  after  exposure  in  a  shallow  dish  to  a 
temperature  of  650  degrees  F.  for  three  (3)  hours,  shall  not  exceed 
10%  of  the  original  weight.  The  oil,  freed  from  water,  shall  be 
wholly  soluble  in  carbon  disulphide. 

Preservative  Treatment. 

98.  The  paving  blocks  shall,  after  they  are  cut  to  the  proper 
dimensions,  be  subjected  to  preservative  treatment,  as  follows: 

The  blocks,  thrown  loosely  into  an  open-work  iron  receptacle, 
or  truck,  shall  be  placed  in  an  iron  or  steel  vessel  or  cylinder,  and 
subjected  to  heat,  gradually  rising  to  a  temperature  not  below  255 
degrees  F.,  nor  above  265  degrees  F.,  and  this  temperature  shall 
be  maintained  for  a  period  of  four  hours.  The  temperature  shall 
then  be  allowed  to  decline  to  about  240  degrees  F.  The  air  shall 
then  be  exhausted  from  the  cylinder  until  a  vacuum  of  not  less 
than  twenty-four  (24)  inches  is  produced,  and  the  creosote  oil 
specified  in  Article  97,  at  a  temperature  of  about  200  degrees  F., 
shall  be  admitted  to  the  cylinder,  the  vacuum  being  maintained 
during  the  admission  of  the  oil.  When  the  blocks  are  all  well 
submerged  in  the  oil  the  vacuum  shall  be  discontinued,  and 
hydraulic  pressure  of  not  less  than  one  hundred  (100)  pounds 
per  square  inch  shall  be  gradually  applied,  and  continued  for  not 
less  than  two  (2)  hours,  or  until  every  part  of  each  block  shall 
be  permeated  with  the  oil,  all  the  blocks  being  kept  submerged  in 
the  oil  until  the  completion  of  the  process. 

The  quantity  of  creosote  oil  in  the  blocks,  after  treatment, 
shall  be  at  least  ten  (10)  pounds  per  cubic  foot  of  wood.*  The 
remaining  oil  shall  then  be  withdrawn  and  the  blocks  removed  from 
the  cylinder. 

In  the  preliminary  heating  of  the  blocks,  either  dry  heat  pro- 
duced by  steam  coils  in  the  cylinder  may  be  employed,  or  steam  at 
a  pressure  of  thirty  (30)  pounds  per  square  inch  may  be  admitted 
directly  into  the  cylinder  and  that  pressure  maintained  for  a  period 
of  four  (4)  hours.  In  either  case  the  extracted  sap  and  condensed 
fluids  must  be  kept  drained  from  the  cylinder. 


*The  only  office  of  the  preservative  treatment  is  to  prevent,  or  at 
least  to  retard,  natural  decay,  since  it  is  well  understood  that  none  of 
the  common  preservative  processes  adds  anything  to  the  strength  and 
wearing  qualities  of  the  wood.  It  follows  that  the  thoroughness  of  the 
treatment  should  be  inversely  as  the  time  the  pavement  is  expected  to 
last.  For  streets  of  light  travel,  where  the  pavement  would  not  wear  out 
short  of  twelve  or  fifteen  years,  the  treatment  should  be  very  thorough, 
and  15  to  20  pounds  of  oil  per  cubic  foot  should  be  injected,  dependent 
upon  the  capacity  of  the  wood  to  absorb  the  oil;  on  the  contrary, 
where  the  travel  is  so  heavy  that  the  pavement  cannot  be  expected  to 
endure  for  more  than  five  to  seven  years,  the  preservative  treatment 
is  not  so  important,  and  the  injection  of  eight  or  ten  pounds  of  oil 
per  cubic  foot  would  usually  be  ample. 


51 

Special  Processes. 

99.  Special  preservative  processes  involving  the  use  of  resin, 
pitch  or  other  substances  admixed  with  creosote  oil,  may  be  used, 
provided  that  the  treated  wood  shall  contain  not  less  than  ten  (10) 
pounds  of  creosote  oil  per  cubic  foot  of  wood,  and  provided  further 
that  the  substances  thus  mixed  with  the  creosote  oil  shall  not,  in 
the  judgment  of   the  Engineer,   be   in   themselves  deleterious,   and 
shall  not  in  any  way  neutralize  the  value  and  preservative  properties 
of  creosote  oil.     The  Engineer  may  require  such  evidence  and  make 
such  tests  at  the  expense  of  the  Contractor  as  will  satisfy  him  upon 
these  points.* 

Laying  the  AVood-Blocks. 

100.  Upon  the  concrete  foundation  shall  be  spread  a  layer  of 
mortar  made  of  one    (1)    part  of  Portland  cement,  and  three    (3) 
parts  of  sand,  complying  with  Sects.  26  and  27,  with  sufficient  water 
to  make  a  moderately  stiff  paste,  f     The  mortar  shall  be  thoroughly 
mixed,  and  shall  be  spread  in  place  on  the  foundation  immediately 
in  advance  of  the  block  laying,  to  such  a  thickness  that  when  the 
blocks  are  set  and  properly  bedded  in  the  mortar  their  tops  shall 
conform  accurately  to  the  designed  grade  and  contour  of  the  street. 
The  concrete  foundation  shall  be  cleaned  and  swept  to  remove  all 
extraneous  matter  and  shall  then  be  thoroughly  dampened,  imme- 
diately in  advance  of  placing  the  mortar  bed.     The  mortar  bed  shall 
be  "struck"  by  templates  to  a  surface  truly  parallel  to  the  pavement 
datum. 

Upon  this  mortar  bed  the  blocks  shall  be  carefully  set  on  end, 
or  with  their  fiber  vertical,  in  straight,  parallel  courses,  either 
perpendicular  to  the  axis  of  the  street,  or  at  such  angle  thereto 
as  the  Engineer  may  direct.  The  blocks  shall  be  set  as  closely 


*The  writer  has  little  confidence  in  the  beneficial  effect  of  adding 
resin,  coal  tar,  or  other  substances  to  the  dead  oil,  and  would  require 
that  a  sufficient  quantity  of  the  oil  should  be  injected  to  itself  pre- 
serve the  wood.  It  is  true  that  pine  woods  when  completely  saturated 
with  resin  (as  they  are  often  found  in  nature)  are  almost  completely 
preserved  from  decay,  but  when  the  wood  is  imperfectly  saturated,  the 
resin  seems  to  have  but  little  effect,  and  it  is  very  difficult,  if  not  im- 
possible, to  produce  complete  saturation  by  artificial  processes.  The 
claim  that  the  use  of  the  resin  prevents  moisture  from  entering-  the 
wood,  might,  if  true,  make  its  use  important.  The  claim  is  undoubtedly 
true  of  freshly  treated  whole  blocks,  since  the  surface  is  coated  and 
sealed  against  water.  But  the  resin  does  not  penetrate  or  saturate 
the  pores  of  the  wood  to  much  depth,  and  when  the  blocks  become 
slightly  worn  and  their  fibers  "broomed,"  they  absorb  water  almost  as 
freely  as  plain  creosoted  wood.  The  sealing  effect  is,  therefore,  but 
temporary  and  of  little  value. 

tit  is  a  common  practice  of  contractors  in  some  cities,  in  the  laying 
of  both  wood  block  and  asphalt  block  pavement,  where  a  mortar  bed  is 
called  for,  to  substitute  a  bed  of  mixed  sand  and  cement,  dampened  only 
to  such  a  degree  as  will  make  the  mass  pulverulent  like  damp  sand, 
the  claim  being  made  that  ordinary  mortar  cannot  be  spread  and 
gaged  properly.  This  claim  is  unfounded.  The  objection  to  the  prac- 
tice is  that  the  dampened  mixture  does  not  contain  sufficient  water  to 
cause  the  cement  to  set,  and  with  the  practically  water-tight  paving 
surface,  does  not  receive,  even  in  rainy  weather,  the  necessary  amount 
of  water.  If  the  weather  be  dry,  the  small  quantity  of  moisture  in  the 
mixture  quickly  evaporates,  leaving  the  so-called  mortar  bed  not  much 
better  than  a  layer  of  sand  alone.  The  writer  has  found  such  alleged 
mortar  soft  and  unset  two  weeks  after  the  pavement  had  been  compl^t- 
ed.  If  real  mortar  is  not  to  be  used,  a  layer  of  sand  might  almost  as 
well  be  substituted  at  first. 


52 

together  as  practicable.  After  the  blocks  are  thus  set  in  place,  they 
shall  be  rammed  with  a  street  rammer  weighing  not  less  than  thirty 
(30)  pounds,  a  plank  ten  (10)  inches  wide,  two  (2)  inches  thick 
and  not  more  than  six  (6)  feet  long,  laid  flat  on  the  pavement, 
being  interposed  between  the  rammer  and  the  blocks  and  moved 
about  until  the  blocks  are  rammed  to  a  firm  seat  in  the  mortar  bed 
and  their  tops  brought  truly  to  the  designed  pavement  datum.  The 
ramming  shall  be  completed  before  the  mortar  bed  has  begun  to 
set,  but  no  ramming  shall  approach  nearer  than  three  (3)  feet  to 
the  edge  of  the  block  setting,  except  where  the  block  setting  may 
be  interrupted,  as  at  the  end  of  a  day's  work,  when  all  the  blocks 
then  set  shall  be  rammed.  Mortar  that  may  have  begun  to  set  before 
the  blocks  are  in  place  and  rammed  shall  be  discarded  and  replaced 
with  fresh  mortar.  The  top  surface  of  the  pavement,  when  laid, 
shall  conform  truly  to  the  grade  and  contour  of  the  street.  Cor- 
rectly-formed templates  twelve  (12)  feet  long,  placed  on  the  pave- 
ment, shall  show  at  no  place  a  departure  of  more  than  three- 
sixteenths  (3-16)  inch  from  the  true  pavement  datum. 

101.  After  the  block  setting  is  completed,  perfectly  dry  fine  sand 
shall  be  spread  over  the  pavement  surface  and  swept  about  until 
every  joint  into  which  the  sand  will  penetrate  shall  be  completely 
filled.     The  remaining  sand  shall  be  left  upon  the  pavement  for  such 
time  as  the  Engineer  may  direct,  when  it  shall  be  removed  by  the 
Contractor.* 

Chamfered  Blocks. 

102.  Where  wood-block  pavement  is  laid  on  streets  or  parts 
of  streets  having  a  gradient  of  more  than  3  % ,  the  blocks  shall  not 
be  less  than  four  (4)  inches  long,  and  the  upper  side-corners  of  the 
blocks  shall   be  chamfered  to  a  depth  of  three-eighths    (  %  )    inch, 
the   chamfered  surface   to   make  an  angle   of   40    degrees   with  the 
vertical   sides   of   the   blocks;    or   such   other   construction   shall   be 
used  as  will,   in   the   opinion  of  the  Engineer,   provide   an   equally 
good  foot-hold  for  horses. 

Expansion  Joints. 

103.  Before   the   blocks   are   set  there   shall   be   placed   along 
and    against   each    curb    a    board    having    a    width    two    (2)    inches 
greater  than  the  depth  of  the  blocks,  three-fourths   (  %  )   inch  thick 
at  its  top  edge  and  one-half    (  y2  )    inch   thick  at  its  bottom   edge. 
The  paving  blocks  at  the  beginning  and  end  of  each  course  shall  be 
set  against  this  board.     After  the  ramming  of  the  blocks  has  been 
completed,  these  boards  shall  be  carefully  withdrawn  and  the  space 
between  the  curbs  and  the  paving  blocks  shall  be  completely  filled 
with  the  bituminous  paving  cement  described  in  Section  76. 

104.  The  street  shall  not  be  opened  to  travel  until  such  time 
as  the  mortar  under  the  blocks  shall  have  become  well  set,  nor  until 
the  Engineer  shall  so  direct. 

*In  a  number  of  cities  the  specifications  require  the  joints  in  wood- 
block pavement  to  be  filled  with  Portland  cement  grout.  If  the  blocks 
are  set  as  closely  together  as  they  should  be,  the  joints  will  be  so  narrow 


53 

GENERAL,  RELATING  TO  ALL  PAVEMENTS. 

Connection  With  Existing  Pavements  or  Streets. 

105.  Wherever   a   new   pavement   joins   or   abuts   against   an 
existing  pavement  of  a  different  kind,  or  an  unpaved  street,  either 
at  the  end  of  the  new  pavement  or  at  cross  or  intersecting  streets, 
a  line  of  stone  headers  shall  be  provided  and  set.     The  stone  shall 
be  of  sound,  hard  limestone,  sandstone,  granite  or  bluestone,  free 
from   injurious   imperfections.      The   separate   stones   shall   be   not 
less  than  three  (3)  feet  long,  not  less  than  four  and  one-  half  (4*£) 
inches  wide  at  the  top,  nor  less  than  three  (3)   inches  wide  at  the 
bottom.     The  top  shall  be  of  uniform  width  for  each  line  of  headers, 
and  shall  be  dressed  square  and  even.     The  ends  shall  be  dressed 
to  secure  a  joint  not  wider  than  one-half  ( ^  )   inch  for  a  depth  of 
six  inches  from  the  top,  and  the  sides  dressed  so  as  to  secure  good 
contact  and  close  jointing  with  the  pavement.     The  stones  shall  be 
set  with  their  tops  at  the  pavement  datum,  on  a  bed  of  concrete 
nine  (9)   inches  wide  and  six   (6)   inches  deep,  and  after  being  set 
the  trench  shall   be   filled   and   rammed   full   of   gravel  or   crushed 
stone. 

All  existing  pavements  adjoining  or  abutting  against  the  new 
pavement,  with  their  crosswalks,  curbs  and  gutters,  shall  be 
adjusted,  or  taken  up  and  relaid,  to  conform  to  and  connect  with 
the  pavement  datum,  to  such  an  extent  as  the  Engineer  may  direct. 

Where  the  new  and  adjoining  pavement  are  of  the  same  kind, 
and  headers  are  not  used,  the  new  and  the  old  pavement  must  be 
properly  joined  and  connected,  as  the  Engineer  may  direct. 

106.  Stone  headers  will  be  paid  for  by  the  linear  foot  at  the 
contract  price  for  that  item,  and  the  other  work  embraced  in  this 
section  will  be  paid  for  at  the  contract  prices  for  the  several  items, 
where  such  contract  prices  are  provided;   otherwise  the  work  shall, 
be  considered  as  incidental  work  and  shall  be  done  at  the  expense 
of  the  Contractor. 

Measurement  and  Estimates. 

107.  Pavements  will  be  paid  for  by  the  square  yard  of  actual 
surface   completed   and   accepted,   deducting   all   sewer,   manhole  or 
other  openings  in  it  of  two  ( 2 )  square  feet  or  more  in  area.     Open- 
ings under  two   (2)   square  feet  in  area  will  be  measured  and  esti- 
mated as  a  part  of  the  pavement  surface. 

The  price  paid  per  square  yard  for  pavement  shall  cover  and 
include  the  supplying  of  all  the  materials  required  and  all  the  labor 
necessary  to  fully  complete  the  work,  except  such  materials  and 

that  no  grout,  thick  enough  in  consistency  to  be  of  value,  will  enter 
them,  except  for  a  short  distance  down  from  the  top,  the  remaining 
depth  of  the  joints  remaining  unfilled. 

An  examination  of  any  well-laid  wood-block  pavement  soon  after 
it  has  been  attempted  to  fill  the  joints  with  grout  will  verify  this  state- 
ment. Furthermore,  the  oil  which  exudes  from  the  blocks,  acting  on  the 
thin  films  of  grout,  seems  to  deterioriate  the  mortar  and  to  render  it 
practically  inert.  On  the  contrary,  fine  dry  sand  will  readily  run  into 
and  completely  fill  the  joints,  and  under  travel  the  joints  will  soon  be- 
come impervious  to  water.  The  sand  filling  is  therefore  regarded  as 
better,  and  it  costs  less  than  the  grout  filling. 


54 

labor  for  which  unit  or  lump  sum  prices  are  provided  and  named  in 
the  contract.      In  the  case  of  asphalt  pavement  the   price   for   the 
pavement  shall  cover  both  the  base  and  the  surface  courses. 
Guaranty.  * 

108.  The   Contractor   shall    guarantee    that   all   the   materials 
used  and  all  the  work  done  under  this  contract  shall  fully  comply 
with  the  requirements  of  these  specifications,  the  plans  hereinbefore 
referred  to  and  the  instructions  of  the  Engineer.      Any  defects  in 
the  completed  work,  or  any  part  of  it,  or  any  failure  of  the  work 
to  fully  perform  or  endure  the  service  for  which  it  was  intended, 
which,  in  the  opinion  of  the  Engineer,  are  attributable  to  the  use 
of  materials,  skill,  or  workmanship  not  in  compliance  with  the  said 
specifications,  plans  and  instructions,  that  may  appear  in  the  work, 

or   any  part  of  it,   within   a   period  of years 

after  the  date  of  the  certificate  of  completion  and  acceptance,  shall 
be  regarded  as  prima  lacie  and  conclusive  evidence  that  the  Con- 
tractor has  failed  to  comply  with  the  said  specifications,  plans  and 
instructions.     And  the  Contractor  shall,  at  his  own  expense,  at  such 
time  and  in  such  manner  as  the  Engineer  may  direct,  repair  or  take 
up  and  reconstruct  any  such  defective  work,  in  full  compliance  with 
the  original  specifications,   plans  and   instructions.      And   as  surety 
for  the  performance  of  this  guaranty  the  Contractor's  bond,  required 
by  the  contract,  shall  remain  in  full  force  until  the  expiration  of 
the  period  of years  above  stipulated  in  this  sec- 
tion. 

Terms  of  Payment. 

109.  Upon  the  last  day  of  each  full  calendar  month  in  which 
the  work  shall  have  been  in  progress,   the  Engineer  will  estimate 
approximately  the  quantities  of  material  delivered  and  of  work  done, 
preceding  that  date,  and  determine  the  percentage  which  the  value 
of  the  materials  delivered  and  the  work  thus  done  is  of  the  estimated 
value  of  the  whole  work,  at  the  contract  prices,  when  completed. 
Eighty  per  cent,  of  the  value  so  determined,  less  any  previous  pay- 
ments made,  will  be  paid  to  the  Contractor  on  or  before  the  fifteenth 
day  of  the  succeeding  month.     But  such  partial  payments  shall  not 
be  construed  as  an  acceptance  by  the  city  of  any  materials  furnished 
or  work  done. 

Within  thirty  days  after  the  final  completion  of  the  work,  and 
its  acceptance  by  the  Engineer,  as  evidenced  by  his  final  estimate  and 
certificate  of  completion  and  acceptance,  any  balance  remaining  due 
to  the  Contractor  will  be  paid  to  him,  provided  that  such  certificate 
of  acceptance  and  final  payment  shall  in  no  way  invalidate  or  release 
the  Contractor  from  the  provisions  of  Section  108. 


*As  outlined  in  the  introduction,  these  specifications  are  designed 
to  secure  the  construction  of  the  pavement  in  a  proper  manner,  the 
city  assuming  responsibility  for  the  character  and  utility  of  the  work. 
The  guarantee  here  proposed  is  therefore  intended  to  cover  only  a 
proper  compliance  with  the  specifications,  for  which  the  contractor  may 
properly  be  held  responsible,  and  not  the  sufficiency  or  utility  of  the 
work,  if  constructed  according  to  the  specifications.  The  period  of 
guaranty  should  therefore  be  short,  not  exceeding  two  years. 


55 


GENERAL  SPECIFICATIONS  FOR  EXPERIMENTAL  OR  UNTRIED 

PAVEMENTS.* 

110.  Contractors  or   promoters   submitting   proposals   for   the 
construction  of  new,  experimental,  or  special  street  pavements,  the 
merits  of  which  have  not  been  established  by  experience  in  the  city 

of ,  must  submit  with  their 

proposal  a  full  and  complete  set  of  specifications  for  the  construction 
of  the  pavement.     If  contract  shall  be  awarded  under  said  proposal, 
said  specifications  will  be  made  a  part  of  the  contract  entered  into. 
The  Engineer  will  enforce  compliance  with  these  specifications,  as 
the  construction  work  proceeds,  without  assuming  or  incurring  any 
responsibility  for  the  character,  quality,  serviceability  or  durability 
of  the   resulting   pavement.      But   the   Contractor   shall   be  subject 
to  and  shall  comply  with  the  requirements  and  stipulations  of  Sects. 
1  to  22,  inclusive,  and  of  Sects.  105,  106  and  107,  of  these  specifica- 
tions. 

Special  Guaranty. 

111.  Inasmuch  as  the  pavement  to  be  constructed  under  the 
special  specifications  submitted  by  the  Contractor  is  more  or  less 
of  an  experimental  character,  having  not  been  heretofore  used  in  the 

city  of to  an  extent  sufficient 

to  establish  its  value,  the  Contractor  shall  be  held  whollv  respon- 
sible for  the  utility,  serviceability  and  durability  of  the  pavement 
so  constructed;   and  he  shall  enter  into  a  guaranty  to  the  effect  as 
follows: 

That  the  pavement  will  fulfill  all  the  usual  and  legitimate 
requirements  of  a  satisfactory  roadway  pavement  upon  the  street 
upon  which  it  is  to  be  laid. 

That  the  pavement  will  successfully  serve  and  endure  the 
travel  to  which  the  street  may  be  subjected  for  a  period  of 
years  next  following  the  date  of  the  certifi- 
cate of  its  completion  and  acceptance,  and  shall  be  in  good  condition 
at  the  end  of  that  period,  ordinary  and  reasonable  wear  and  tear, 
and  accidental  or  other  injuries  not  due  to  defects  in  the  pavement 
itself,  excepted. 

That  the  Contracto'r  will,  at  his  own  cost,  keep  the  said  pave- 
ment in  satisfactory  repair  during  said  period  of 

years,  and  will  leave  it  in  a  condition  of  satisfactory  repair  at  the 
end  of  that  period. 


Upon  the  general  subject  of  time  guarantees  of  municipal  work, 
see  Chapter  XI,  "Municipal  Public  Works,"  by  the  writer. 

*In  this  class  of  pavements  the  contractor  or  promoter  may  prop- 
erly be  required  to  assume  responsibility  for  the  character  and  utility 
of  the  work  produced,  and  the  municipal  authorities  should  assume  no 
part  of  such  responsibility. 


56 

That  the  Engineer,  or  his  successor  or  successors  in  office,  shall 
be  the  sole  and  final  judge  as  to  whether  the  conditions  of  this 
guaranty  shall  be,  or  shall  have  been  complied  with. 

That  in  case  the  pavement  shall  not,  in  the  judgment  of  the 
Engineer,  fulfill  the  terms  and  conditions  of  this  guaranty  at  any 

time  during  said  period  of years,  or  upon 

its  expiration,  or  in  case  the  Contractor  shall  fail  to  make  all  or  any 
of  the  repairs  that  may  in  the  judgment  of  the  Engineer  be  or 

become  necessary  during  said   period   of years, 

within  a  reasonable  period  to  be  determined  by  the  Engineer,  but 
not  to  be  less  than  twenty  (20)  days  after  notice  to  make  such 
repairs  has  been  given  him  by  the  Engineer,  he  (the  Engineer)  may 
proceed  to  make  or  to  have  made  such  repairs,  or  to  repave  the 
street,  in  any  manner  that  he  may  deem  necessary  or  advisable,  and 
to  charge  the  cost  of  such  repairs  or  repavement  to  the  Contractor, 
provided,  that  the  sum  or  sums  so  charged  against  the  Contractor 
shall  not,  in  the  aggregate,  be  more  than  the  amount  paid  to  the 
Contractor  for  the  construction  of  the  pavement. 
Bond. 

112.  The  Contractor  shall  give  bond  with  sureties  satisfactory 
to  the  Engineer  in  a  sum  not  less  than  the  estimated  cost  of  the 
pavement  at  the  contract  prices,  the  term  of  the  bond  to  extend  over 
the  entire  period  of years,  for  which  the  pave- 
ment is  guaranteed. 

113.  During  the  said  period  of years 

the  Contractor  shall,  upon  being  notified  by  the  Engineer  so  to  do, 
make  any  repairs  to  the  pavement  that  may  become  necessary  by 
reason  of  cutting  into  it  for  the  purpose  of  constructing  or  repairing 
pipes,  conduits  or  other  underground  structures,  or  street  railroad 
tracks,  or  by  reason  of  accidental  or  unusual  causes,  or  of  any  causes 
other  than  those  due,  in  the  opinion  of  the  Engineer,  to  the  failure 
of   the    pavement   to    meet    and    fulfill    the    terms   of   the    guaranty 
stipulated  in  Section  111. 

And  for  making  such  repairs  the  Contractor  shall  be  paid  the 

price  of per  square  yard  of  the 

repairs  actually  so  made.  Repairs  so  made  shall  be  subject  to  the 
terms  of  the  guaranty,  stipulated  in  Section  111,  until  the  expiration 

of  the  said  term  of years  after  the  date  of  the 

original  certificate  of  completion  and  acceptance.  In  case  the  Con- 
tractor shall  neglect  or  fail  to  make  such  repairs  within  a  period 
of  twenty  (20)  days  after  he  shall  have  received  notice  to  do  so, 
the  Engineer  may  proceed  to  make  or  to  have  made  such  repairs, 
and  he  shall  charge  to  and  collect  from  the  Contractor  the  cost  of 
the  repairs  so  made. 


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